Method for transmitting/receiving data in wireless communication system, and device for supporting same

ABSTRACT

The disclosure proposes a method for transmitting/receiving data in a wireless communication system and apparatus for supporting the same. Specifically, a method of transmitting an uplink data channel by a user equipment (UE) in a wireless communication system comprises receiving, from a base station, first downlink control information for scheduling an uplink data channel in an nth transmission time unit, receiving, from the base station, second downlink control information for scheduling an uplink data channel in an n+kth transmission time unit, and when information by the first downlink control information is inconsistent with information by the second downlink control information, transmitting an uplink data channel which is based on the first downlink control information to the base station, wherein the second downlink control information may be discarded by the UE.

TECHNICAL FIELD

The disclosure relates to a method for transmitting and receiving datain a wireless communication system and, more particularly, to a methodof transmitting and receiving a downlink channel and/or an uplinkchannel and an apparatus supporting the same.

BACKGROUND ART

Mobile communication systems have been developed to provide voiceservices, while ensuring the activity of users. However, coverage of themobile communication systems has extended up to data services, as wellas voice service. Today, an explosive increase in traffic has caused theshortage of resources. Accordingly, an advanced mobile communicationsystem is necessary because users want relatively high speed services.

Requirements for a next-generation mobile communication system includethe accommodation of explosive data traffic, a significant increase inthe transfer rate per user, the accommodation of the number ofconsiderably increased connection devices, very low end-to-end latency,and high energy efficiency. To this end, research of varioustechnologies, such as dual connectivity, massive multiple input multipleoutput (MIMO), in-band full duplex, non-orthogonal multiple access(NOMA), super wideband, and device networking, is carried out.

DETAILED DESCRIPTION OF THE DISCLOSURE Technical Problems

The disclosure provides a method of transmitting and receiving adownlink channel and/or an uplink channel.

Specifically, the disclosure provides a method of scheduling and/ortransmitting and receiving a downlink channel by considering the sharingand/or repetition of a demodulation reference signal (DMRS) in relationto the transmission and reception of the downlink channel.

The disclosure aims to provide a method of perform uplink channeltransmission/reception based on specific downlink control informationconsidering that there is a setting and/or indication in which aplurality of pieces of downlink control information are inconsistentwith each other in relation to uplink channel transmission/reception.

Technical objects to be achieved in the disclosure are not limited tothe above-described technical objects, and other technical objects notdescribed above may be evidently understood by a person having ordinaryskill in the art to which the disclosure pertains from the followingdescription.

Technical Solutions

According to an embodiment of the disclosure, a method of transmittingan uplink data channel by a user equipment (UE) in a wirelesscommunication system comprises receiving, from a base station, firstdownlink control information for scheduling an uplink data channel in annth transmission time unit, receiving, from the base station, seconddownlink control information for scheduling an uplink data channel in ann+kth transmission time unit, and when information by the first downlinkcontrol information is inconsistent with information by the seconddownlink control information, transmitting an uplink data channel whichis based on the first downlink control information to the base station,wherein the second downlink control information may be discarded by theUE.

According to an embodiment of the disclosure, in the method, the firstdownlink control information and the second downlink control informationeach may include at least one of information for a demodulationreference signal (DMRS) pattern related to the uplink data channel,information for a cyclic shift, information for interleaved frequencydivision multiple access (IFDMA) comb, information for a resourceallocation, information for precoding, and/or information for the numberof layers.

According to an embodiment of the disclosure, in the method, when theinformation by the first downlink control information is inconsistentwith the information by the second downlink control information, aninconsistency may occur in the DMRS pattern information.

According to an embodiment of the disclosure, in the method, the DMRSpattern included in the first downlink control information may indicateDMRS transmission for the uplink data channel at a first symbol in then+kth transmission time unit, and the DMRS pattern included in thesecond downlink control information may not indicate DMRS transmissionfor the uplink data channel at the first symbol in the n+kthtransmission time unit.

According to an embodiment of the disclosure, in the method, when theinformation by the first downlink control information is inconsistentwith the information by the second downlink control information, aninconsistency may occur in at least one of the cyclic shift information,the IFDMA comb information, the resource allocation information, theprecoding information, and/or the number-of-layers information.

According to an embodiment of the disclosure, in the method, the DMRSpattern included in the first downlink control information and the DMRSpattern included in the second downlink control information may indicateDMRS transmission for the uplink data channel at the first symbol in then+kth transmission time unit.

According to an embodiment of the disclosure, in the method, k may be 1,and the nth transmission time unit may be placed continuously with then+kth transmission time unit.

According to an embodiment of the disclosure, in the method, the nthtransmission time unit and the n+kth transmission time unit each may bea subslot including two or three orthogonal frequency divisionmultiplexing (OFDM) symbols.

According to an embodiment of the disclosure, a user equipment (UE)transmitting an uplink data channel in a wireless communication systemcomprises a transceiver for transmitting or receiving a wireless signaland a processor functionally connected with the transceiver, wherein theprocessor may performs control to receive, from a base station, firstdownlink control information for scheduling the uplink data channel inan nth transmission time unit, receive, from the base station, seconddownlink control information for scheduling the uplink data channel inan n+kth transmission time unit, and when information by the firstdownlink control information is inconsistent with information by thesecond downlink control information, transmit the uplink data channelwhich is based on the first downlink control information to the basestation, wherein the second downlink control information may bediscarded by the UE.

According to an embodiment of the disclosure, in the UE, the firstdownlink control information and the second downlink control informationeach may include at least one of information for a demodulationreference signal (DMRS) pattern related to the uplink data channel,information for a cyclic shift, information for interleaved frequencydivision multiple access (IFDMA) comb, information for a resourceallocation, information for precoding, and/or information for the numberof layers.

According to an embodiment of the disclosure, in the UE, when theinformation by the first downlink control information is inconsistentwith the information by the second downlink control information, aninconsistency may occur in the DMRS pattern information.

According to an embodiment of the disclosure, in the UE, the DMRSpattern included in the first downlink control information may indicateDMRS transmission for the uplink data channel at a first symbol in then+kth transmission time unit, and the DMRS pattern included in thesecond downlink control information may not indicate DMRS transmissionfor the uplink data channel at the first symbol in the n+kthtransmission time unit.

According to an embodiment of the disclosure, in the UE, when theinformation by the first downlink control information is inconsistentwith the information by the second downlink control information, aninconsistency may occur in at least one of the cyclic shift information,the IFDMA comb information, the resource allocation information, theprecoding information, and/or the number-of-layers information.

According to an embodiment of the disclosure, in the UE, the DMRSpattern included in the first downlink control information and the DMRSpattern included in the second downlink control information may indicateDMRS transmission for the uplink data channel at the first symbol in then+kth transmission time unit.

According to an embodiment of the disclosure, a base station receivingan uplink data channel in a wireless communication system comprises atransceiver for transmitting or receiving a wireless signal and aprocessor functionally connected with the transceiver, wherein theprocessor may perform control to transmit, to a user equipment (UE),first downlink control information for scheduling the uplink datachannel in an nth transmission time unit, transmit, to the UE, seconddownlink control information for scheduling the uplink data channel inan n+kth transmission time unit, and when information by the firstdownlink control information is inconsistent with information by thesecond downlink control information, receive, from the UE, the uplinkdata channel which is based on the first downlink control information,wherein the second downlink control information may be discarded by theUE.

Advantageous Effects

According to an embodiment of the disclosure, there is an effect in thatthe ambiguity of a user equipment operation which may occur when a DMRSindicated by DCI, etc. is absent or present can be removed by clarifyinga behavior of a user equipment related to DMRS sharing.

Furthermore, according to an embodiment of the disclosure, there is aneffect in that an operation for 3-layer or more PDSCHs is made possibleand/or a reduction in the data rate can be prevented by clarifying abehavior of a user equipment related to a DMRS repetition.

According to an embodiment of the disclosure, it is possible to addressthe UE's behavior ambiguity even when inconsistent settings and/orindications are transferred by a plurality of pieces of downlink controlinformation.

Effects which may be obtained in the disclosure are not limited to theabove-described effects, and other technical effects not described abovemay be evidently understood by a person having ordinary skill in the artto which the disclosure pertains from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and constitute a part of the detaileddescription, illustrate embodiments of the disclosure and together withthe description serve to explain the principle of the disclosure.

FIG. 1 illustrates the structure of a radio frame in a wirelesscommunication system to which the disclosure may be applied.

FIG. 2 illustrates a resource grid for one downlink slot in a wirelesscommunication system to which the disclosure may be applied.

FIG. 3 illustrates the structure of a downlink subframe in a wirelesscommunication system to which the disclosure may be applied.

FIG. 4 illustrates the structure of an uplink subframe in a wirelesscommunication system to which the disclosure may be applied.

FIG. 5 illustrates an example of an overall structure of a NR system towhich a method proposed in the disclosure may be applied.

FIG. 6 illustrates a relation between an uplink frame and a downlinkframe in a wireless communication system to which a method proposed inthe disclosure may be applied.

FIG. 7 illustrates an example of a frame structure in a NR system.

FIG. 8 illustrates an example of a resource grid supported in a wirelesscommunication system to which a method proposed in the disclosure may beapplied.

FIG. 9 illustrates examples of a resource grid per antenna port andnumerology to which a method proposed in the disclosure may be applied.

FIG. 10 illustrates an example of a self-contained structure to which amethod proposed in the disclosure may be applied.

FIG. 11 illustrates an example in which physical uplink control channel(PUCCH) formats are mapped to PUCCH regions of uplink physical resourceblocks in a wireless communication system to which the disclosure may beapplied.

FIG. 12 illustrates the structure of a channel quality indicator (CQI)channel in the case of a normal cyclic prefix (CP) in a wirelesscommunication system to which the disclosure may be applied.

FIG. 13 illustrates the structure of ACK/NACK channel in the case of anormal CP in a wireless communication system to which the disclosure maybe applied.

FIG. 14 illustrates an example of transport channel processing of anuplink shared channel (UL-SCH) in a wireless communication system towhich the disclosure may be applied.

FIG. 15 illustrates an example of the signal processing of an uplinkshared channel that is a transport channel in a wireless communicationsystem to which the disclosure may be applied.

FIG. 16 illustrates an example of generating and transmitting 5 SC-FDMAsymbols during one slot in a wireless communication system to which thedisclosure may be applied.

FIG. 17 illustrates an ACK/NACK channel structure for PUCCH format 3with a normal CP.

FIG. 18 is a flowchart illustrating example operations of a UE todetermine whether to receive a downlink data channel to which a methodproposed according to an embodiment is applicable.

FIG. 19 is a flowchart illustrating example operations of a base stationto transmit a downlink data channel to which a method proposed accordingto an embodiment is applicable;

FIG. 20 is a flowchart illustrating example operations of a UE totransmit an uplink data channel to which a method proposed according toan embodiment is applicable;

FIG. 21 is a flowchart illustrating example operations of a base stationto receive an uplink data channel to which a method proposed accordingto an embodiment is applicable;

FIG. 22 is a block diagram illustrating a configuration of a wirelesscommunication device to which methods proposed according to thedisclosure are applicable.

FIG. 23 is a block diagram illustrating another example configuration ofa wireless communication device to which methods proposed according tothe disclosure are applicable.

MODE FOR CARRYING OUT THE DISCLOSURE

Hereafter, preferred embodiments of the disclosure will be described indetail with reference to the accompanying drawings. A detaileddescription to be disclosed hereinafter together with the accompanyingdrawing is to describe embodiments of the disclosure and not to describea unique embodiment for carrying out the disclosure. The detaileddescription below includes details in order to provide a completeunderstanding. However, those skilled in the art know that thedisclosure can be carried out without the details.

In some cases, in order to prevent a concept of the disclosure frombeing ambiguous, known structures and devices may be omitted or may beillustrated in a block diagram format based on core function of eachstructure and device.

In the disclosure, a base station means a terminal node of a networkdirectly performing communication with a terminal. In the presentdocument, specific operations described to be performed by the basestation may be performed by an upper node of the base station in somecases. That is, it is apparent that in the network constituted bymultiple network nodes including the base station, various operationsperformed for communication with the terminal may be performed by thebase station or other network nodes other than the base station. A basestation (BS) may be generally substituted with terms such as a fixedstation, Node B, evolved-NodeB (eNB), a base transceiver system (BTS),an access point (AP), and the like. Further, a ‘terminal’ may be fixedor movable and be substituted with terms such as user equipment (UE), amobile station (MS), a user terminal (UT), a mobile subscriber station(MSS), a subscriber station (SS), an advanced mobile station (AMS), awireless terminal (WT), a Machine-Type Communication (MTC) device, aMachine-to-Machine (M2M) device, a Device-to-Device (D2D) device, andthe like.

Hereinafter, a downlink means communication from the base station to theterminal and an uplink means communication from the terminal to the basestation. In the downlink, a transmitter may be a part of the basestation and a receiver may be a part of the terminal. In the uplink, thetransmitter may be a part of the terminal and the receiver may be a partof the base station.

Specific terms used in the following description are provided to helpappreciating the disclosure and the use of the specific terms may bemodified into other forms within the scope without departing from thetechnical spirit of the disclosure.

The following technology may be used in various wireless access systems,such as code division multiple access (CDMA), frequency divisionmultiple access (FDMA), time division multiple access (TDMA), orthogonalfrequency division multiple access (OFDMA), single carrier-FDMA(SC-FDMA), non-orthogonal multiple access (NOMA), and the like. The CDMAmay be implemented by radio technology universal terrestrial radioaccess (UTRA) or CDMA2000. The TDMA may be implemented by radiotechnology such as Global System for mobile communications (GSM)/generalpacket radio service (GPRS)/enhanced data rates for GSM evolution(EDGE). The OFDMA may be implemented as radio technology such as IEEE802.11(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, evolved UTRA (E-UTRA),and the like. The UTRA is a part of a universal mobile telecommunicationsystem (UMTS). 3rd generation partnership project (3GPP) long termevolution (LTE) as a part of an evolved UMTS (E-UMTS) using evolved-UMTSterrestrial radio access (E-UTRA) adopts the OFDMA in a downlink and theSC-FDMA in an uplink. LTE-advanced (A) is an evolution of the 3GPP LTE.

The embodiments of the disclosure may be based on standard documentsdisclosed in at least one of IEEE 802, 3GPP, and 3GPP2 which are thewireless access systems. That is, steps or parts which are not describedto definitely show the technical spirit of the disclosure among theembodiments of the disclosure may be based on the documents. Further,all terms disclosed in the document may be described by the standarddocument.

3GPP LTE/LTE-A is primarily described for clear description, buttechnical features of the disclosure are not limited thereto.

Overview of System

FIG. 1 illustrates the structure of a radio frame in a wirelesscommunication system to which the disclosure may be applied.

3GPP LTE/LTE-A supports radio frame structure type 1 applicable tofrequency division duplex (FDD) and radio frame structure Type 2applicable to time division duplex (TDD).

In FIG. 1, the size of a radio frame in a time domain is represented asa multiple of a time unit of T_s=1/(15000*2048). Downlink and uplinktransmissions are organized into radio frames with a duration ofT_f=307200*T_s=10 ms.

FIG. 1(a) illustrates radio frame structure type 1. The radio framestructure type 1 may be applied to both full duplex FDD and half duplexFDD.

A radio frame consists of 10 subframes. One radio frame consists of 20slots of T_slot=15360*T_s=0.5 ms length, and indexes of 0 to 19 aregiven to the respective slots. One subframe consists of two consecutiveslots in the time domain, and subframe i consists of slot 2i and slot2i+1. A time required to transmit one subframe is referred to as atransmission time interval (TTI). For example, the length of onesubframe may be 1 ms, and the length of one slot may be 0.5 ms.

The uplink transmission and the downlink transmission in the FDD aredistinguished in the frequency domain. Whereas there is no restrictionin the full duplex FDD, a UE cannot transmit and receive simultaneouslyin the half duplex FDD operation.

One slot includes a plurality of orthogonal frequency divisionmultiplexing (OFDM) symbols in the time domain and includes a pluralityof resource blocks (RBs) in a frequency domain. Since 3GPP LTE usesOFDMA in downlink, OFDM symbols are used to represent one symbol period.The OFDM symbol may be called one SC-FDMA symbol or a symbol period. Theresource block is a resource allocation unit and includes a plurality ofconsecutive subcarriers in one slot.

FIG. 1(b) illustrates frame structure type 2.

The radio frame type 2 consists of two half-frames of 153600*T_s=5 mslength each. Each half-frame consists of five subframes of 30720*T_s=1ms length.

In the frame structure type 2 of a TDD system, uplink-downlinkconfiguration is a rule indicating whether uplink and downlink areallocated (or reserved) to all subframes.

Table 1 represents uplink-downlink configuration.

TABLE 1 Downlink- to-Uplink Uplink- Switch- Downlink point Subframenumber configuration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U DS U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms DS U U U D D D D D 4 10 ms D S U U D D D D D D 5 10 ms D S U D D D D D DD 6 5 ms D S U U U D S U U D

Referring to Table 1, in each subframe of the radio frame, ‘D’represents a subframe for downlink transmission, ‘U’ represents asubframe for uplink transmission, and ‘S’ represents a special subframeconsisting of three types of fields including a downlink pilot time slot(DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS). TheDwPTS is used for an initial cell search, synchronization or channelestimation in a UE. The UpPTS is used for channel estimation in a basestation and uplink transmission synchronization of the UE. The GP is aperiod for removing interference generated in uplink due to multi-pathdelay of a downlink signal between uplink and downlink.

Each subframe i consists of slot 2i and slot 2i+1 ofT_slot=15360*T_s=0.5 ms length each.

The uplink-downlink configuration may be classified into 7 types, and alocation and/or the number of a downlink subframe, a special subframeand an uplink subframe are different for each configuration.

A point of time at which switching from downlink to uplink or switchingfrom uplink to downlink is performed is referred to as a switchingpoint. A switch-point periodicity refers to a period in which switchedpatterns of an uplink subframe and a downlink subframe are equallyrepeated, and both 5 ms and 10 ms switch-point periodicity aresupported. In case of 5 ms downlink-to-uplink switch-point periodicity,the special subframe S exists in every half-frame. In case of 5 msdownlink-to-uplink switch-point periodicity, the special subframe Sexists in a first half-frame only.

In all the configurations, subframes 0 and 5 and a DwPTS are reservedfor downlink transmission only. An UpPTS and a subframe immediatelyfollowing the subframe are always reserved for uplink transmission.

Such uplink-downlink configurations may be known to both the basestation and the UE as system information. The base station may informthe UE of change in an uplink-downlink allocation state of a radio frameby transmitting only indexes of uplink-downlink configurationinformation to the UE each time the uplink-downlink configurationinformation is changed. Furthermore, configuration information is a kindof downlink control information and may be transmitted via a physicaldownlink control channel (PDCCH) like other scheduling information, oris a kind of broadcast information and may be commonly transmitted toall UEs within a cell via a broadcast channel.

Table 2 represents configuration (length of DwPTS/GP/UpPTS) of a specialsubframe.

TABLE 2 Normal cyclic prefix Extended cyclic prefix in downlink indownlink UpPTS UpPTS Normal Extended Normal Extended Special cycliccyclic cyclic cyclic subframe prefix in prefix in prefix in prefix inconfiguration DwPTS uplink uplink DwPTS uplink uplink 0  6592 · T_(s)2192 · T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s) 119760 · T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 ·T_(s) 25600 · T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 ·T_(s) 5  6592 · T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 ·T_(s) 23040 · T_(s) 7 21952 · T_(s) — — — 8 24144 · T_(s) — — —

The structure of a radio frame according to an example of FIG. 1 ismerely an example, and the number of subcarriers included in a radioframe, the number of slots included in a subframe, and the number ofOFDM symbols included in a slot may be variously changed.

FIG. 2 is a diagram illustrating a resource grid for one downlink slotin the wireless communication system to which the disclosure may beapplied.

Referring to FIG. 2, one downlink slot includes the plurality of OFDMsymbols in the time domain. Herein, it is exemplarily described that onedownlink slot includes 7 OFDM symbols and one resource block includes 12subcarriers in the frequency domain, but the disclosure is not limitedthereto.

Each element on the resource grid is referred to as a resource elementand one resource block includes 12×7 resource elements. The number ofresource blocks included in the downlink slot, NDL is subordinated to adownlink transmission bandwidth.

A structure of the uplink slot may be the same as that of the downlinkslot.

FIG. 3 illustrates the structure of a downlink subframe in the wirelesscommunication system to which the disclosure may be applied.

Referring to FIG. 3, a maximum of three former OFDM symbols in the firstslot of the sub frame is a control region to which control channels areallocated and residual OFDM symbols is a data region to which a physicaldownlink shared channel (PDSCH) is allocated. Examples of the downlinkcontrol channel used in the 3GPP LTE include a physical control formatindicator channel (PCFICH), a Physical Downlink Control Channel (PDCCH),a Physical Hybrid-ARQ Indicator Channel (PHICH), and the like.

The PFCICH is transmitted in the first OFDM symbol of the subframe andtransports information on the number (that is, the size of the controlregion) of OFDM symbols used for transmitting the control channels inthe subframe. The PHICH which is a response channel to the uplinktransports an Acknowledgement (ACK)/Not-Acknowledgement (NACK) signalfor a hybrid automatic repeat request (HARQ). Control informationtransmitted through a PDCCH is referred to as downlink controlinformation (DCI). The downlink control information includes uplinkresource allocation information, downlink resource allocationinformation, or an uplink transmission (Tx) power control command for apredetermined terminal group.

The PDCCH may transport A resource allocation and transmission format(also referred to as a downlink grant) of a downlink shared channel(DL-SCH), resource allocation information (also referred to as an uplinkgrant) of an uplink shared channel (UL-SCH), paging information in apaging channel (PCH), system information in the DL-SCH, resourceallocation for an upper-layer control message such as a random accessresponse transmitted in the PDSCH, an aggregate of transmission powercontrol commands for individual terminals in the predetermined terminalgroup, a voice over IP (VoIP). A plurality of PDCCHs may be transmittedin the control region and the terminal may monitor the plurality ofPDCCHs. The PDCCH is constituted by one or an aggregate of a pluralityof continuous control channel elements (CCEs). The CCE is a logicalallocation wise used to provide a coding rate depending on a state of aradio channel to the PDCCH. The CCEs correspond to a plurality ofresource element groups. A format of the PDCCH and a bit number ofusable PDCCH are determined according to an association between thenumber of CCEs and the coding rate provided by the CCEs.

The base station determines the PDCCH format according to the DCI to betransmitted and attaches a cyclic redundancy check (CRC) to the controlinformation. The CRC is masked with a unique identifier (referred to asa radio network temporary identifier (RNTI)) according to an owner or apurpose of the PDCCH. In the case of a PDCCH for a specific terminal,the unique identifier of the terminal, for example, a cell-RNTI (C-RNTI)may be masked with the CRC. Alternatively, in the case of a PDCCH forthe paging message, a paging indication identifier, for example, the CRCmay be masked with a paging-RNTI (P-RNTI). In the case of a PDCCH forthe system information, in more detail, a system information block(SIB), the CRC may be masked with a system information identifier, thatis, a system information (SI)-RNTI. The CRC may be masked with a randomaccess (RA)-RNTI in order to indicate the random access response whichis a response to transmission of a random access preamble.

An enhanced PDCCH (EPDCCH) carries UE-specific signaling. The EPDCCH islocated in a physical resource block (PRB) that is configured to be UEspecific. In other words, as described above, the PDCCH may betransmitted in up to first three OFDM symbols in a first slot of asubframe, but the EPDCCH may be transmitted in a resource region otherthan the PDCCH. A time (i.e., symbol) at which the EPDCCH starts in thesubframe may be configured to the UE via higher layer signaling (e.g.,RRC signaling).

The EPDCCH may carry a transport format, resource allocation and HARQinformation related to DL-SCH, a transport format, resource allocationand HARQ information related to UL-SCH, resource allocation informationrelated to sidelink shared channel (SL-SCH) and physical sidelinkcontrol channel (PSCCH), etc. Multiple EPDCCHs may be supported, and theUE may monitor a set of EPCCHs.

The EPDCCH may be transmitted using one or more consecutive enhancedCCEs (ECCEs), and the number of ECCEs per EPDCCH may be determined foreach EPDCCH format.

Each ECCE may consist of a plurality of enhanced resource element groups(EREGs). The EREG is used to define mapping of the ECCE to the RE. Thereare 16 EREGs per PRB pair. All REs except the RE carrying the DMRS ineach PRB pair are numbered from 0 to 15 in increasing order of thefrequency and then in increasing order of time.

The UE may monitor a plurality of EPDCCHs. For example, one or twoEPDCCH sets may be configured in one PRB pair in which the UE monitorsEPDCCH transmission.

Different coding rates may be implemented for the EPCCH by combiningdifferent numbers of ECCEs. The EPCCH may use localized transmission ordistributed transmission, and hence, the mapping of ECCE to the RE inthe PRB may vary.

FIG. 4 illustrates the structure of an uplink subframe in the wirelesscommunication system to which the disclosure may be applied.

Referring to FIG. 4, the uplink subframe may be divided into the controlregion and the data region in a frequency domain. A physical uplinkcontrol channel (PUCCH) transporting uplink control information isallocated to the control region. A physical uplink shared channel(PUSCH) transporting user data is allocated to the data region. Oneterminal does not simultaneously transmit the PUCCH and the PUSCH inorder to maintain a single carrier characteristic.

A resource block (RB) pair in the subframe is allocated to the PUCCH forone terminal. RBs included in the RB pair occupy different subcarriersin two slots, respectively. The RB pair allocated to the PUCCHfrequency-hops in a slot boundary.

The following disclosure proposed by the disclosure can be applied to a5G NR system (or device) as well as a LTE/LTE-A system (or device).

Communication of the 5G NR system is described below with reference toFIGS. 5 to 10.

The 5G NR system defines enhanced mobile broadband (eMBB), massivemachine type communications (mMTC), ultra-reliable and low latencycommunications (URLLC), and vehicle-to-everything (V2X) based on usagescenario (e.g., service type).

A 5G NR standard is divided into standalone (SA) and non-standalone(NSA) depending on co-existence between a NR system and a LTE system.

The 5G NR system supports various subcarrier spacings and supportsCP-OFDM in the downlink and CP-OFDM and DFT-s-OFDM (SC-OFDM) in theuplink.

Embodiments of the disclosure can be supported by standard documentsdisclosed in at least one of IEEE 802, 3GPP, and 3GPP2 which are thewireless access systems. That is, steps or parts in embodiments of thedisclosure which are not described to clearly show the technical spiritof the disclosure can be supported by the standard documents. Further,all terms disclosed in the disclosure can be described by the standarddocument.

As smartphones and Internet of Things (IoT) terminals spread rapidly, anamount of information exchanged through a communication network isincreasing. Hence, it is necessary to consider an environment (e.g.,enhanced mobile broadband communication) that provides faster servicesto more users than the existing communication system (or existing radioaccess technology) in the next generation wireless access technology.

To this end, a design of a communication system considering machine typecommunication (MTC) that provides services by connecting multipledevices and objects is being discussed. In addition, a design of acommunication system (e.g., ultra-reliable and low latency communication(URLLC) considering a service and/or a terminal sensitive to reliabilityand/or latency of communication is also being discussed.

Hereinafter, in the disclosure, for convenience of description, the nextgeneration radio access technology is referred to as NR (new RAT, radioaccess technology), and a wireless communication system to which the NRis applied is referred to as an NR system.

Definition of NR system related terms

eLTE eNB: The eLTE eNB is the evolution of eNB that supportsconnectivity to EPC and NGC.

gNB: A node which supports the NR as well as connectivity to NGC.

New RAN: A radio access network which supports either NR or E-UTRA orinterfaces with the NGC.

Network slice: A network slice is a network defined by the operatorcustomized to provide an optimized solution for a specific marketscenario which demands specific requirements with end-to-end scope.

Network function: A network function is a logical node within a networkinfrastructure that has well-defined external interfaces andwell-defined functional behavior.

NG-C: A control plane interface used on NG2 reference points between newRAN and NGC.

NG-U: A user plane interface used on NG3 reference points between newRAN and NGC.

Non-standalone NR: A deployment configuration where the gNB requires anLTE eNB as an anchor for control plane connectivity to EPC, or requiresan eLTE eNB as an anchor for control plane connectivity to NGC.

Non-standalone E-UTRA: A deployment configuration where the eLTE eNBrequires a gNB as an anchor for control plane connectivity to NGC.

User plane gateway: A termination point of NG-U interface.

FIG. 5 illustrates an example of an overall structure of a NR system towhich a method proposed in the disclosure may be applied.

Referring to FIG. 5, an NG-RAN consists of gNBs that provide an NG-RAuser plane (new AS sublayer/PDCP/RLC/MAC/PHY) and control plane (RRC)protocol terminations for a user equipment (UE).

The gNBs are interconnected with each other by means of an Xn interface.

The gNBs are also connected to an NGC by means of an NG interface.

More specifically, the gNBs are connected to an access and mobilitymanagement function (AMF) by means of an N2 interface and to a userplane function (UPF) by means of an N3 interface.

NR (New Rat) Numerology and Frame Structure

In a NR system, multiple numerologies can be supported. A numerology maybe defined by a subcarrier spacing and a cyclic prefix (CP) overhead.Multiple subcarrier spacings can be derived by scaling a basicsubcarrier spacing by an integer N (or μ). Further, although it isassumed not to use a very low subcarrier spacing at a very high carrierfrequency, the numerology used can be selected independently of afrequency band.

In the NR system, various frame structures according to the multiplenumerologies can be supported.

Hereinafter, an orthogonal frequency division multiplexing (OFDM)numerology and a frame structure which may be considered in the NRsystem will be described.

Multiple OFDM numerologies supported in the NR system may be defined asin Table 3.

TABLE 3 μ Δf = 2^(μ) · 15[kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal, Extended 3 120 Normal 4 240 Normal

In regard to a frame structure in the NR system, a size of variousfields in a time domain is expressed as a multiple of a time unit ofT_(s)=1/(Δf_(max)·N_(f)), where Δf_(max)=480·10³ and N_(f)=4096 Downlinkand uplink transmissions are organized into radio frames with a durationof T_(f)=(Δf_(max)N_(f)/100)·T_(s)=10 ms. In this case, the radio frameconsists of ten subframes each having a duration ofT_(sf)=(Δf_(max)N_(f)/1000)·T_(s)=1 ms. In this case, there may be a setof frames in the uplink and a set of frames in the downlink. FIG. 6illustrates a relation between an uplink frame and a downlink frame in awireless communication system to which a method proposed in thedisclosure may be applied.

As illustrated in FIG. 6, uplink frame number i for transmission from auser equipment (UE) shall start T_(TA)=N_(TA)T_(s) before the start of acorresponding downlink frame at the corresponding UE.

Regarding the numerology μ, slots are numbered in increasing order ofn_(s) ^(μ)∈{0, . . . , N_(subframe) ^(slots,μ)−1} within a subframe andare numbered in increasing order of n_(s,f) ^(μ)∈{0, . . . , N_(frame)^(slots,μ)−1} within a radio frame. One slot consists of consecutiveOFDM symbols of N_(symb) ^(μ), and N_(symb) ^(μ) is determined dependingon a numerology used and slot configuration. The start of slots n_(s)^(μ) in a subframe is aligned in time with the start of OFDM symbolsn_(s) ^(μ)N_(symb) ^(μ) in the same subframe.

Not all UEs are able to transmit and receive at the same time, and thismeans that not all OFDM symbols in a downlink slot or an uplink slot areavailable to be used.

Table 4 represents the number N_(symb) ^(slot) of OFDM symbols per slot,the number N_(slot) ^(frame,μ) of slot of slots per radio frame, and thenumber N_(slot) ^(subframe,μ) of slots per subframe in a normal CP.Table 5 represents the number of OFDM symbols per slot, the number ofslots per radio frame, and the number of slots per subframe in anextended CP.

TABLE 4 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16

TABLE 5 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)2 12 40 4

FIG. 7 illustrates an example of a frame structure in a NR system. FIG.7 is merely for convenience of description and does not limit the scopeof the disclosure. In Table 5, in the case of μ=2, i.e., as an examplein which a subcarrier spacing (SCS) is 60 kHz, one subframe (or frame)may include four slots with reference to Table 4, and one subframe={1,2, 4} slots shown in FIG. 3, for example, the number of slot(s) that maybe included in one subframe may be defined as in Table 2.

Further, a mini-slot may consist of 2, 4, or 7 symbols, or may consistof more symbols or less symbols.

In regard to physical resources in the NR system, an antenna port, aresource grid, a resource element, a resource block, a carrier part,etc. may be considered.

Hereinafter, the above physical resources that can be considered in theNR system are described in more detail.

First, in regard to an antenna port, the antenna port is defined so thata channel over which a symbol on an antenna port is conveyed can beinferred from a channel over which another symbol on the same antennaport is conveyed. When large-scale properties of a channel over which asymbol on one antenna port is conveyed can be inferred from a channelover which a symbol on another antenna port is conveyed, the two antennaports may be regarded as being in a quasi co-located or quasico-location (QC/QCL) relation. In this case, the large-scale propertiesmay include at least one of delay spread, Doppler spread, frequencyshift, average received power, and received timing.

FIG. 8 illustrates an example of a resource grid supported in a wirelesscommunication system to which a method proposed in the disclosure may beapplied.

Referring to FIG. 8, a resource grid consists of N_(RB) ^(μ)N_(sc) ^(RB)subcarriers on a frequency domain, each subframe consisting of 14·2μOFDM symbols, but the disclosure is not limited thereto.

In the NR system, a transmitted signal is described by one or moreresource grids, consisting of N_(RB) ^(μ)N_(sc) ^(RB) subcarriers, and2^(μ)N_(symb) ^((μ)) OFDM symbols, where N_(RB) ^(μ)≤N_(RB) ^(max,μ).N_(RB) ^(max,μ) denotes a maximum transmission bandwidth and may changenot only between numerologies but also between uplink and downlink.

In this case, as illustrated in FIG. 9, one resource grid may beconfigured per numerology μ and antenna port p.

FIG. 9 illustrates examples of a resource grid per antenna port andnumerology to which a method proposed in the disclosure may be applied.

Each element of the resource grid for the numerology μ and the antennaport p is called a resource element and is uniquely identified by anindex pair (k,l), where k=0, . . . , N_(RB) ^(μ)N_(sc) ^(RB)−1 is anindex on a frequency domain, and l=0, . . . , 2^(μ)N_(symb) ^((μ))−1refers to a location of a symbol in a subframe. The index pair (k,l) isused to refer to a resource element in a slot, where l=0, . . . ,N_(symb) ^(μ)−1.

The resource element (k,l) for the numerology P and the antenna port pcorresponds to a complex value a_(k,l) ^((p,μ)). When there is no riskfor confusion or when a specific antenna port or numerology is notspecified, the indexes p and μ may be dropped, and as a result, thecomplex value may be a_(k,l) ^((p)) or a_(k,l) .

Further, a physical resource block is defined as N_(sc) ^(RB)=12consecutive subcarriers in the frequency domain.

Point A serves as a common reference point of a resource block grid andmay be obtained as follows.

-   -   offsetToPointA for PCell downlink represents a frequency offset        between the point A and a lowest subcarrier of a lowest resource        block that overlaps a SS/PBCH block used by the UE for initial        cell selection, and is expressed in units of resource blocks        assuming 15 kHz subcarrier spacing for FR1 and 60 kHz subcarrier        spacing for FR2;    -   absoluteFrequencyPointA represents frequency-location of the        point A expressed as in absolute radio-frequency channel number        (ARFCN).

The common resource blocks are numbered from 0 and upwards in thefrequency domain for subcarrier spacing configuration μ.

The center of subcarrier 0 of common resource block 0 for the subcarrierspacing configuration μ coincides with ‘point A’. A common resourceblock number n_(CRB) ^(μ) in the frequency domain and resource elements(k,l) for the subcarrier spacing configuration μ may be given by thefollowing Equation 1.

$\begin{matrix}{n_{CRB}^{\mu} = \left\lfloor \frac{k}{N_{sc}^{RB}} \right\rfloor} & {{Equation}\mspace{14mu} 1}\end{matrix}$

In this case, k may be defined relative to the point A so that k=0corresponds to a subcarrier centered around the point A. Physicalresource blocks are defined within a bandwidth part (BWP) and arenumbered from 0 to N_(BWP,i) ^(size)−1, where i is No. of the BWP. Arelation between the physical resource block n_(PRB) in BWP i and thecommon resource block n_(CRB) may be given by the following Equation 2.

n _(CRB) =n _(PRB) +N _(BWP,i) ^(start)  Equation 2

In this case, N_(BWP,i) ^(start) may be the common resource block wherethe BWP starts relative to the common resource block 0.

Self-Contained Structure

A time division duplexing (TDD) structure considered in the NR system isa structure in which both uplink (UL) and downlink (DL) are processed inone slot (or subframe). The structure is to minimize a latency of datatransmission in a TDD system and may be referred to as a self-containedstructure or a self-contained slot.

FIG. 10 illustrates an example of a self-contained structure to which amethod proposed in the disclosure may be applied. FIG. 10 is merely forconvenience of description and does not limit the scope of thedisclosure.

Referring to FIG. 10, as in legacy LTE, it is assumed that onetransmission unit (e.g., slot, subframe) consists of 14 orthogonalfrequency division multiplexing (OFDM) symbols.

In FIG. 10, a region 1002 means a downlink control region, and a region1004 means an uplink control region. Further, regions (i.e., regionswithout separate indication) other than the region 1002 and the region1004 may be used for transmission of downlink data or uplink data.

That is, uplink control information and downlink control information maybe transmitted in one self-contained slot. On the other hand, in thecase of data, uplink data or downlink data is transmitted in oneself-contained slot.

When the structure illustrated in FIG. 10 is used, in one self-containedslot, downlink transmission and uplink transmission may sequentiallyproceed, and downlink data transmission and uplink ACK/NACK receptionmay be performed.

As a result, if an error occurs in the data transmission, time requireduntil retransmission of data can be reduced. Hence, the latency relatedto data transfer can be minimized.

In the self-contained slot structure illustrated in FIG. 10, a basestation (e.g., eNodeB, eNB, gNB) and/or a user equipment (UE) (e.g.,terminal) require a time gap for a process for converting a transmissionmode into a reception mode or a process for converting a reception modeinto a transmission mode. In regard to the time gap, if uplinktransmission is performed after downlink transmission in theself-contained slot, some OFDM symbol(s) may be configured as a guardperiod (GP).

Physical Uplink Control Channel (PUCCH)

Uplink control information (UCI) transmitted on a PUCCH may includescheduling request (SR), HARQ ACK/NACK information, and downlink channelmeasurement information.

The HARQ ACK/NACK information may be produced depending on whetherdecoding of downlink data packet on a PDSCH is successful or not. In theexisting wireless communication system, one ACK/NACK bit is transmittedin the case of single codeword downlink transmission while two ACK/NACKbits are transmitted in the case of two codeword downlink transmissions.

The channel measurement information refers to feedback informationrelated to a multiple input multiple output (MIMO) scheme and mayinclude a channel quality indicator (CQI), a precoding matrix index(PMI), and a rank indicator (RI). The channel measurement informationmay collectively be referred to as a CQI.

20 bits per subframe may be used for the CQI transmission.

The PUCCH may be modulated by using a binary phase shift keying (BPSK)scheme and a quadrature phase shift keying (QPSK) scheme. Controlinformation for a plurality of UEs may be transmitted on the PDCCH. Incase of performing code division multiplexing (CDM) to distinguishsignals of the respective UEs, a length-12 constant amplitude zeroautocorrelation (CAZAC) sequence is mostly used. Since the CAZACsequence has characteristics of maintaining a predetermined amplitude ina time domain and a frequency domain, the CAZAC has properties suitableto increase coverage by reducing a peak-to-average power ratio (PAPR) ora cubic metric (CM) of the UE. In addition, the ACK/NACK information fordownlink data transmission transmitted on the PDCCH is covered by usingan orthogonal sequence or an orthogonal cover (OC).

Further, control information transmitted on the PUCCH may bedistinguished using a cyclically shifted sequence each having adifferent cyclic shift (CS) value. The cyclically shifted sequence maybe produced by cyclically shifting a base sequence by as much as aspecific cyclic shift (CS) amount. The specific CS amount is indicatedby a CS index. The number of available cyclic shifts may vary dependingon the delay spread of a channel. Various kinds of sequences may be usedas the base sequence, and the CAZAC sequence described above is anexample.

An amount of control information that the UE can transmit in onesubframe may be determined depending on the number of SC-FDMA symbols(i.e., SC-FDMA symbols except SC-FDMA symbols used for reference signal(RS) transmission for coherent detection of the PUCCH), that can be usedin the transmission of the control information.

In the 3GPP LTE system, the PUCCH is defined as a total of sevendifferent formats depending on transmitted control information, amodulation scheme, an amount of control information, etc., andattributes of uplink control information (UCI) transmitted according toeach PUCCH format may be summarized as in the following Table 6.

TABLE 6 PUCCH Format Uplink Control Information(UCI) Format 1 SchedulingRequest (SR) (unmodulated waveform) Format 1a 1-bit HARQ ACK/NACKwith/without SR Format 1b 2-bit HARQ ACK/NACK with/without SR Format 2CQI (20 coded bits) Format 2 CQI and 1- or 2-bit HARQ ACK/NACK (20 bits)for extended CP only Format 2a CQI and 1-bit HARQ ACK/NACK (20 + 1 codedbits) Format 2b CQI and 2-bit HARQ ACK/NACK (20 + 2 coded bits)

PUCCH format 1 is used for single transmission of SR. In case of singletransmission of SR, an unmodulated waveform is applied, which will bedescribed below in detail. PUCCH format 1a or 1b is used fortransmission of HARQ ACK/NACK. In case of single transmission of HARQACK/NACK in a random subframe, PUCCH format 1a or 1b may be used.Alternatively, the HARQ ACK/NACK and the SR may be transmitted in thesame subframe using the PUCCH format 1a or 1b.

PUCCH format 2 is used for transmission of a CQI, and PUCCH format 2a or2b is used for transmission of the CQI and the HARQ ACK/NACK.

In case of an extended CP, the PUCCH format 2 may also be used fortransmission of the CQI and the HARQ ACK/NACK.

FIG. 11 illustrates an example in which PUCCH formats are mapped toPUCCH regions of uplink physical resource blocks in a wirelesscommunication system to which the disclosure may be applied.

In FIG. 11, N_(RB) ^(UL) represents the number of resource blocks in theuplink, and 0, 1, . . . , N_(RB) ^(UL)−1 refers to No. of s physicalresource block. Basically, the PUCCH is mapped to both edges of anuplink frequency block. As illustrated in FIG. 11, the PUCCH format2/2a/2b is mapped to a PUCCH region marked by m=0, 1, which mayrepresent that the PUCCH format 2/2a/2b is mapped to resource blockslocated at band edges. In addition, the PUCCH format 2/2a/2b and thePUCCH format 1/1a/1b are interchangeably mapped to the PUCCH regionmarked by m=2. Next, the PUCCH format 1/1a/1b may be mapped to a PUCCHregion marked by m=3, 4, 5. The number N_(RB) ⁽²⁾ of PUCCH RBs availablefor use by the PUCCH format 2/2a/2b may be indicated to the UEs in acell by broadcasting signaling.

The PUCCH format 2/2a/2b is described. The PUCCH format 2/2a/2b is acontrol channel used to transmit channel measurement feedbacks CQI, PMI,and RI.

A periodicity and a frequency unit (or a frequency resolution) to beused to report the channel measurement feedback (hereinafter,collectively referred to as CQI information) may be controlled by thebase station. Periodic CQI reporting and aperiodic CQI reporting in atime domain can be reported. The PUCCH format 2 may be used for theperiodic CQI reporting only, and the PUSCH may be used for the aperiodicCQI reporting. In case of the aperiodic CQI reporting, the base stationmay instruct the UE to send an individual CQI report embedded into aresource which is scheduled for uplink data transmission.

FIG. 12 illustrates the structure of CQI channel in the case of a normalCP in a wireless communication system to which the disclosure may beapplied.

Among SC-FDMA symbols 0 to 6 of one slot, SC-FDMA symbols 1 and 5(second and sixth symbols) may be used for transmission of demodulationreference signal (DMRS), and the CQI information may be transmitted inthe remaining SC-FDMA symbols. In case of the extended CP, one SC-FDMAsymbol (SC-FDMA symbol 3) is used for the DMRS transmission.

In the PUCCH format 2/2a/2b, the modulation by the CAZAC sequence issupported, and a QPSK modulated symbol is multiplied by the length-12CAZAC sequence. A cyclic shift (CS) of the sequence is changed betweensymbols and slots. An orthogonal covering is used for the DMRS.

The reference signal (DMRS) is carried on two SC-FDMA symbols which areseparated from each other at an interval of three SC-FDMA symbols amongseven SC-FDMA symbols included in one slot, and the CQI information iscarried on the remaining five SC-FDMA symbols. The use of two RSs in oneslot is to support a high speed UE. Further, the respective UEs aredistinguished using a cyclic shift (CS) sequence. CQI informationsymbols are modulated and transmitted to all the SC-FDMA symbols, andthe SC-FDMA symbol is composed of one sequence. That is, the UEmodulates the CQI and transmits the modulated CQI to each sequence.

The number of symbols which can be transmitted in one TTI is 10, and themodulation of the CQI information is also determined up to the QPSK.Since a 2-bit CQI value can be carried in the case of using the QPSKmapping for the SC-FDMA symbol, a 10-bit CQI value can be carried on oneslot. Thus, a CQI value of maximum 20 bits can be carried in onesubframe. A frequency domain spreading code is used to spread the CQIinformation in a frequency domain.

As the frequency domain spreading code, length-12 CAZAC sequence (e.g.,ZC sequence) may be used. Each control channel may be distinguished byapplying the CAZAC sequence having a different cyclic shift value. AnIFFT is performed on frequency domain spreading CQI information.

The 12 equally-spaced cyclic shifts may allow 12 different UEs to beorthogonally multiplexed on the same PUCCH RB. In case of a normal CP, aDMRS sequence on the SC-FDMA symbol 1 and 5 (on the SC-FDMA symbol 3 inthe case of an extended CP) is similar to a CQI signal sequence on thefrequency domain, but the modulation like the CQI information is notapplied.

The UE may be semi-statically configured by higher layer signaling toreport periodically different CQI, PMI, and RI types on PUCCH resourcesindicated as PUCCH resource indexes (n_(PUCCH) ^((l,{tilde over (p)}),n_(PUCCH) ^((2,{tilde over (p)})), n_(PUCCH) ^((3,{tilde over (p)}))).In this case, the PUCCH resource index (n_(PUCCH)^((2,{tilde over (p)}))) is information indicating a PUCCH region usedfor the PUCCH format 2/2a/2b transmission and a cyclic shift (CS) valueto be used.

PUCCH Channel Structure

PUCCH formats 1a and 1b are described.

In the PUCCH format 1a/1b, a symbol modulated using a BPSK or QPSKmodulation scheme is multiplied by length-12 CAZAC sequence. Forexample, the result of multiplying length-N CAZAC sequence r(n) (wheren=0, 1, 2, . . . , N−1) by a modulation symbol d(0) is y(0), y(1), y(2),. . . , y(N−1). The symbols y(0), y(1), y(2), . . . , y(N−1) may bereferred to as a block of symbols. After the CAZAC sequence ismultiplied by the modulation symbol, the block-wise spreading using anorthogonal sequence is applied.

A length-4 Hadamard sequence is used for normal ACK/NACK information,and a length-3 discrete Fourier transform (DFT) sequence is used forshortened ACK/NACK information and a reference signal.

A length-2 Hadamard sequence is used for the reference signal in thecase of an extended CP.

FIG. 13 illustrates the structure of ACK/NACK channel in the case of anormal CP in a wireless communication system to which the disclosure maybe applied.

More specifically, FIG. 13 illustrates an example of a PUCCH channelstructure for HARQ ACK/NACK transmission without CQI.

A reference signal (RS) is carried on three consecutive SC-FDMA symbolsin the middle of seven SC-FDMA symbols included in one slot, and anACK/NACK signal is carried on the remaining four SC-FDMA symbols.

In case of an extended CP, the RS may be carried on two consecutivesymbols in the middle. The number and location of symbols used for theRS may vary depending on a control channel, and the number and locationof symbols used for the ACK/NACK signal related may be changedaccordingly.

Both 1-bit and 2-bit acknowledgement information (in a state of notbeing scrambled) may be expressed as a single HARQ ACK/NACK modulationsymbol using the BPSK and QPSK modulation schemes, respectively.Positive acknowledgement (ACK) may be encoded as ‘1’, and negative ACK(HACK) may be encoded as ‘0’.

When a control signal is transmitted in an allocated bandwidth,two-dimensional spreading is applied to increase a multiplexingcapacity. That is, frequency domain spreading and time domain spreadingare simultaneously applied to increase the number of UEs or the numberof control channels that can be multiplexed.

In order to spread an ACK/NACK signal in the frequency domain, afrequency domain sequence is used as a base sequence. As the frequencydomain sequence, a Zadoff-Chu (ZC) sequence which is a kind of CAZACsequence may be used. For example, multiplexing of different UEs ordifferent control channels can be applied by applying different cyclicshifts (CS) to the ZC sequence which is the base sequence. The number ofCS resources supported in SC-FDMA symbols for PUCCH RBs for the HARQACK/NACK transmission is configured by a cell-specific higher layersignaling parameter Δ_(shift) ^(PUCCH).

The frequency domain spreading ACK/NACK signal is spread in a timedomain using an orthogonal spreading code. A Walsh-Hadamard sequence ora DFT sequence may be used as the orthogonal spreading code. Forexample, the ACK/NACK signal may be spread using length-4 orthogonalsequences (w0, w1, w2, w3) for four symbols. An RS is also spreadthrough length-3 or length-2 orthogonal sequence. This is referred to asorthogonal covering (OC).

As described above, multiple UEs may be multiplexed in a code divisionmultiplexing (CDM) method using CS resources in the frequency domain andOC resources in the time domain. That is, ACK/NACK information and a RSof a large number of UEs may be multiplexed on the same PUCCH RB.

As to the time domain spreading CDM, the number of spreading codessupported for the ACK/NACK information is limited by the number of RSsymbols. That is, since the number of SC-FDMA symbols for RStransmission is less than the number of SC-FDMA symbols for ACK/NACKinformation transmission, a multiplexing capacity of the RS is less thana multiplexing capacity of the ACK/NACK information.

For example, in the case of the normal CP, the ACK/NACK information maybe transmitted on four symbols, and not four but three orthogonalspreading codes may be used for the ACK/NACK information. The reason forthis is that the number of RS transmission symbols is limited to three,and three orthogonal spreading codes only may be used for the RS.

If three symbols in one slot are used for the RS transmission and foursymbols are used for the ACK/NACK information transmission in a subframeof the normal CP, for example, if six cyclic shifts (CSs) in thefrequency domain and three orthogonal covering (OC) resources in thetime domain can be used, HARQ acknowledgement from a total of 18different UEs may be multiplexed within one PUCCH RB. If two symbols inone slot are used for the RS transmission and four symbols are used forthe ACK/NACK information transmission in a subframe of the extended CP,for example, if six cyclic shifts (CSs) in the frequency domain and twoorthogonal covering (OC) resources in the time domain can be used, HARQacknowledgement from a total of 12 different UEs may be multiplexed inone PUCCH RB.

Next, the PUCCH format 1 is described. A scheduling request (SR) istransmitted in such a manner that the UE is requested to be scheduled oris not request. A SR channel reuses an ACK/NACK channel structure in thePUCCH format 1a/1b, and is configured in an on-off keying (OOK) methodbased on an ACK/NACK channel design. In the SR channel, a referencesignal is not transmitted. Thus, length-7 sequence is used in the normalCP, and length-6 sequence is used in the extended CP. Different cyclicshifts or orthogonal covers may be allocated for the SR and theACK/NACK. That is, the UE transmits HARQ ACK/NACK on resources allocatedfor the SR for the purpose of positive SR transmission. The UE transmitsHARQ ACK/NACK on resources allocated for the ACK/NACK for the purpose ofnegative SR transmission.

Next, an enhanced-PUCCH (e-PUCCH) format is described. The e-PUCCHformat may correspond to PUCCH format 3 of the LTE-A system. A blockspreading scheme may be applied to the ACK/NACK transmission using thePUCCH format 3.

PUCCH Piggybacking in Rel-8 LTE

FIG. 14 illustrates an example of transport channel processing of anUL-SCH in a wireless communication system to which the disclosure may beapplied.

In the 3GPP LTE system (=E-UTRA, Rel. 8), in the case of the UL, forefficient utilization of a power amplifier of a terminal,peak-to-average power ratio (PAPR) characteristics or cubic metric (CM)characteristics that affect a performance of the power amplifier areconfigured so that good single carrier transmission is maintained. Thatis, in the existing LTE system, the good single carrier characteristicscan be maintained by maintaining single carrier characteristics of datato be transmitted through DFT-precoding in the case of the PUSCHtransmission, and transmitting information carried on a sequence withthe single carrier characteristic in the case of the PUCCH transmission.However, when DFT-precoded data is non-consecutively allocated to afrequency axis or the PUSCH and the PUCCH are simultaneouslytransmitted, the single carrier characteristics are degraded. Thus, asillustrated in FIG. 8, when the PUSCH is transmitted in the samesubframe as the PUCCH transmission, uplink control information (UCI) tobe transmitted to the PUCCH for the purpose of maintaining the singlecarrier characteristics is transmitted (piggyback) together with thedata via the PUSCH.

As described above, because the PUCCH and the PUSCH cannot besimultaneously transmitted in the existing LTE terminal, the existingLTE terminal uses a method that multiplexes uplink control information(UCI) (CQI/PMI, HARQ-ACK, RI) to the PUSCH region in a subframe in whichthe PUSCH is transmitted.

For example, when a channel quality indicator (CQI) and/or a precodingmatrix indicator (PMI) needs to be transmitted in a subframe allocatedto transmit the PUSCH, UL-SCH data and the CQI/PMI are multiplexedbefore DFT-spreading to transmit both control information and data. Inthis case, the UL-SCH data performs rate-matching considering CQI/PMIresources. Further, a scheme is used, in which control information suchas HARQ ACK and RI punctures the UL-SCH data and is multiplexed to thePUSCH region.

FIG. 15 illustrates an example of the signal processing of an uplinkshared channel that is a transport channel in a wireless communicationsystem to which the disclosure may be applied.

Hereinafter, signal processing of an uplink shared channel (hereinafter,referred to as “UL-SCH”) may be applied to one or more transportchannels or control information types.

Referring to FIG. 15, the UL-SCH transfers data to a coding unit in theform of a transport block (TB) once every a transmission time interval(TTI).

CRC parity bits p₀, p₁, p₂, p₃, . . . , p_(L-1) are attached to bits a₀,a₁, a₂, a₃, . . . , a_(A-1) of a transport block transferred from theupper layer. In this instance, A denotes a size of the transport block,and L denotes the number of parity bits. Input bits, to which the CRC isattached, are denoted by b₀, b₁, b₂, b₃, . . . , b_(B-1). In thisinstance, B denotes the number of bits of the transport block includingthe CRC.

b₀, b₁, b₂, b₃, . . . , b_(B-1) are segmented into multiple code blocks(CBs) according to the size of the TB, and the CRC is attached to themultiple segmented CBs. Bits after the code block segmentation and theCRC attachment are denoted by c_(r0), c_(r1), c_(r2), c_(r3), . . . ,c_(r(K) _(r) ₋₁₎. In this case, r represents No. (r=0, . . . , C−1) ofthe code block, and Kr represents the number of bits depending on thecode block r. Further, C represents the total number of code blocks.

Subsequently, channel coding is performed. Output bits after the channelcoding are denoted by d_(r0) ^((i)), d_(r1) ^((i)), d_(r2) ^((i)),d_(r3) ^((i)), . . . , d_(r(D) _(r) ₋₁₎ ^((i)). In this instance, idenotes a coded stream index and may have a value of 0, 1, or 2. Drdenotes the number of bits of an i-th coded stream for a code block r. rdenotes a code block number (r=0, . . . , C−1), and C represents thetotal number of code blocks. Each code block may be coded by turbocoding.

Subsequently, rate matching is performed. Bits after the rate matchingare denoted by e_(r0),e_(r1),e_(r2),e_(r3), . . . , e_(r(E) _(r) ₋₁₎. Inthis case, r represents the code block number (r=0, . . . , C−1), and Crepresents the total number of code blocks. Er represents the number ofrate-matched bits of a r-th code block.

Subsequently, concatenation between the code blocks is performed again.Bits after the concatenation of the code blocks is performed are denotedby f₀, f₁, f₂, f₃, . . . , f_(G-1). In this instance, G represents thetotal number of bits coded for transmission, and when the controlinformation is multiplexed with the UL-SCH, the number of bits used forthe transmission of the control information is not included.

When the control information is transmitted on the PUSCH, channel codingof CQI/PMI, RI, and ACK/NACK which are the control information isindependently performed. Because different coded symbols are allocatedfor the transmission of each control information, each controlinformation has a different coding rate.

In time division duplex (TDD), an ACK/NACK feedback mode supports twomodes of ACK/NACK bundling and ACK/NACK multiplexing by higher layerconfiguration. ACK/NACK information bit for the ACK/NACK bundlingconsists of 1 bit or 2 bits, and ACK/NACK information bit for theACK/NACK multiplexing consists of between 1 bit and 4 bits.

After the concatenation between the code blocks, coded bits f₀,f₁,f₂,f₃,. . . ,f_(G-1) of the UL-SCH data and coded bits q₀,q₁,q₂,q₃, . . .,q_(N) _(L) _(·Q) _(CQI) ₋₁ of the CQI/PMI are multiplexed. The resultof multiplexing the data and the CQI/PMI is denoted by g ₀,g ₁,g ₂,g ₃,. . . ,g _(H′-1). In this instance, g _(i) (i=0, . . . , H′−1)represents a column vector with a length of (Q_(m)·N_(L)),H=(G+N_(L)·Q_(CQI)), and H′=H/(N_(L)·Q_(m)). N_(L) represents the numberof layers mapped to a UL-SCH transport block, and H represents the totalnumber of coded bits allocated, for the UL-SCH data and the CQI/PMIinformation, to N_(L) transport layers to which the transport block ismapped.

Subsequently, multiplexed data and CQI/PMI, separately channel-coded RI,and ACK/NACK are channel-interleaved to generate an output signal.

PDCCH Assignment Procedure

A plurality of PDCCHs may be transmitted within one subframe. That is, acontrol region of one subframe consists of a plurality of CCEs havingindexes 0 to N_(CCE,k)−1, where N_(CCE,k) denotes the total number ofCCEs in a control region of a k-th subframe. The UE monitors a pluralityof PDCCHs in every subframe. In this case, the monitoring means that theUE attempts the decoding of each PDCCH depending on a monitored PDCCHformat. The base station does not provide the UE with information aboutwhere the corresponding PDCCH is in a control region allocated in asubframe. Since the UE cannot know which position its own PDCCH istransmitted at which CCE aggregation level or DCI format in order toreceive a control channel transmitted by the base station, the UEmonitors a set of PDCCH candidates in the subframe and searches its ownPDCCH. This is called blind decoding/detection (BD). The blind decodingrefers to a method, by the UE, for de-masking its own UE identifier (UEID) from a CRC part and then checking whether a corresponding PDCCH isits own control channel by reviewing a CRC error.

In an active mode, the UE monitors a PDCCH of each subframe in order toreceive data transmitted to the UE. In a DRX mode, the UE wakes up in amonitoring interval of each DRX period and monitors a PDCCH in asubframe corresponding to the monitoring interval. A subframe in whichthe monitoring of the PDCCH is performed is called a non-DRX subframe.

The UE shall perform the blind decoding on all of CCEs present in acontrol region of the non-DRX subframe in order to receive the PDCCHtransmitted to the UE. Since the UE does not know which PDCCH formatwill be transmitted, the UE shall decode all of PDCCHs at a possible CCEaggregation level until the blind decoding of the PDCCHs is successfulwithin each non-DRX subframe. Since the UE does not know how many CCEsare used for the PDCCH for the UE, the UE shall attempt detection at allthe possible CCE aggregation levels until the blind decoding of thePDCCH is successful. That is, the UE performs the blind decoding per CCEaggregation level. That is, the UE first attempts decoding by setting aCCE aggregation level unit to 1. If all the decoding fails, the UEattempts decoding by setting the CCE aggregation level unit to 2.Thereafter, the UE attempts decoding by setting the CCE aggregationlevel unit to 4 and setting the CCE aggregation level unit to 8.Furthermore, the UE attempts the blind decoding on a total of four ofC-RNTI, P-RNTI, SI-RNTI, and RA-RNTI. The UE attempts blind decoding onall the DCI formats that need to be monitored.

As described above, if the UE performs blind decoding on all thepossible RNTIs and all the DCI formats, that need to be monitored, pereach of all the CCE aggregation levels, the number of detection attemptsexcessively increases. Therefore, in the LTE system, a search space (SS)concept is defined for the blind decoding of the UE. The search spacemeans a set of PDCCH candidates for monitoring, and may have a differentsize depending on each PDCCH format.

The search space may include a common search space (CSS) and aUE-specific/dedicated search space (USS). In the case of the commonsearch space, all the UEs may be aware of the size of the common searchspace, but the UE-specific search space may be individually configuredto each UE. Thus, the UE must monitor both the UE-specific search spaceand the common search space in order to decode the PDCCH, and thusperforms blind decoding (BD) up to 44 times in one subframe. This doesnot include blind decoding performed based on a different CRC value(e.g., C-RNTI, P-RNTI, SI-RNTI, RA-RNTI).

A case where the base station cannot secure CCE resources fortransmitting a PDCCH to all the UEs which intend to transmit the PDCCHwithin a given subframe due to a small search space may occur. Thereason for this is that resources left over after a CCE location isallocated may not be included in a search space of a specific UE. Inorder to minimize such a barrier that may continue even in a nextsubframe, a UE-specific hopping sequence may be applied to the point atwhich the UE-specific search space starts.

Table 7 represents the size of the common search space and theUE-specific search space.

TABLE 7 Number of Number of Number candidates candidates PDCCH of CCEsin common in dedicated format (n) search space search space 0 1 — 6 1 2— 6 2 4 4 2 3 8 2 2

In order to reduce a computational load of a UE according to the numberof times that the UE attempts blind decoding, the UE does not performsearch according to all of defined DCI formats at the same time.Specifically, the UE may always perform search for DCI formats 0 and 1Ain the UE-specific search space. In this instance, the DCI formats 0 and1A have the same size, but the UE may distinguish between the DCIformats using a flag for the DCI format 0/format 1A differentiationincluded in a PDCCH. Furthermore, DCI formats other than the DCI formats0 and 1A may be required for the UE depending on a PDSCH transmissionmode configured by the base station. For example, DCI formats 1, 1B and2 may be used.

The UE in the common search space may search for the DCI formats 1A and1C. Furthermore, the UE may be configured to search for the DCI format 3or 3A. The DCI formats 3 and 3A have the same size as the DCI formats 0and 1A, but the UE may distinguish between the DCI formats using CRSscrambled by another identifier not a UE-specific identifier.

A search space S_(k) ^((L)) means a set of PDCCH candidates according toan aggregation level L∈{1,2,4,8}. A CCE according to a PDCCH candidateset m of the search space may be determined by the following Equation 3.

L·{(Y _(k) +m) mod └N _(CCE,k) /L┘}+i  Equation 3

In this case, M^((L)) represents the number of PDCCH candidatesaccording to a CCE aggregation level L for monitoring in the searchspace, and m=0, . . . , M^((L))−1. i is an index for designating anindividual CCE in each PDCCH candidate, where i=0, . . . , L−1.

As described above, the UE monitors both the UE-specific search spaceand the common search space in order to decode the PDCCH. In this case,the common search space (CSS) supports PDCCHs with an aggregation levelof {4, 8}, and the UE-specific search space (USS) supports PDCCHs withan aggregation level of {1, 2, 4, 8}.

Table 8 represents DCCH candidates monitored by a UE.

TABLE 8 Search space S_(k) ^((L)) Number of Aggregation Size PDCCH Typelevel L [in CCEs] candidates M^((L)) UE- 1 6 6 specific 2 12 6 4 8 2 816 2 Common 4 16 4 8 16 2

Referring to Equation 3, in the case of the common search space, Y_(k)is set to 0 with respect to two aggregation levels L=4 and L=8. On theother hand, in the case of the UE-specific search space with respect toan aggregation level L, Y_(k) is defined as in Equation 4

Y _(k)=(A·Y _(k-1)) mod D  Equation 4

In this case, Y⁻¹=n_(RNTI)≠0, and an RNTI value used for n_(RNTI) may bedefined as one of identifications of the UE. Further, A=39827, D=65537,and k=└n_(s)/2┘, where n_(s) denotes a slot number (or index) in a radioframe.

General ACK/NACK Multiplexing Method

In a situation in which a UE shall simultaneously transmit multipleACKs/NACKs corresponding to multiple data units received from an eNB, anACK/NACK multiplexing method based on PUCCH resource selection may beconsidered to maintain single-frequency characteristics of an ACK/NACKsignal and reduce ACK/NACK transmission power.

Together with ACK/NACK multiplexing, contents of ACK/NACK responses formultiple data units are identified by combining a PUCCH resource and aresource of QPSK modulation symbols used for actual ACK/NACKtransmission.

For example, if one PUCCH resource transmits 4 bits and up to four dataunits can be transmitted, an ACK/NACK result can be identified at theeNB as indicated in the following Table 9.

TABLE 9 HARQ-ACK(0), HARQ-ACK(1), HARQ-ACK(2), HARQ-ACK(3) n_(PUCCH) ⁽¹⁾b(0), b(1) ACK, ACK, ACK, ACK n_(PUCCH, 1) ⁽¹⁾ 1, 1 ACK, ACK, ACK,NACK/DTX n_(PUCCH, 1) ⁽¹⁾ 1, 0 NACK/DTX, NACK/DTX, NACK, DTXn_(PUCCH, 2) ⁽¹⁾ 1, 1 ACK, ACK, NACK/DTX, ACK n_(PUCCH, 1) ⁽¹⁾ 1, 0NACK, DTX, DTX, DTX n_(PUCCH, 0) ⁽¹⁾ 1, 0 ACK, ACK, NACK/DTX, NACK/DTXn_(PUCCH, 1) ⁽¹⁾ 1, 0 ACK, NACK/DTX, ACK, ACK n_(PUCCH, 3) ⁽¹⁾ 0, 1NACK/DTX, NACK/DTX, NACK/DTX, n_(PUCCH, 3) ⁽¹⁾ 1, 1 NACK ACK, NACK/DTX,ACK, NACK/DTX n_(PUCCH, 2) ⁽¹⁾ 0, 1 ACK, NACK/DTX, NACK/DTX, ACKn_(PUCCH, 0) ⁽¹⁾ 0, 1 ACK, NACK/DTX, NACK/DTX, NACK/DTX n_(PUCCH, 0) ⁽¹⁾1, 1 NACK/DTX, ACK, ACK, ACK n_(PUCCH, 3) ⁽¹⁾ 0, 1 NACK/DTX, NACK, DTX,DTX n_(PUCCH, 1) ⁽¹⁾ 0, 0 NACK DTX, ACK, ACK, NACK/DTX n_(PUCCH, 2) ⁽¹⁾1, 0 NACK/DTX, ACK, NACK/DTX, ACK n_(PUCCH, 3) ⁽¹⁾ 1, 0 NACK/DTX, ACK,NACK/DTX, NACK/DTX n_(PUCCH, 1) ⁽¹⁾ 0, 1 NACK/DTX, NACK/DTX, ACK, ACKn_(PUCCH, 3) ⁽¹⁾ 0, 1 NACK/DTX, NACK/DTX, ACK, NACK/DTX n_(PUCCH, 2) ⁽¹⁾0, 0 NACK/DTX, NACK/DTX, NACK/DTX, ACK n_(PUCCH, 3) ⁽¹⁾ 0, 0 DTX, DTX,DTX, DTX N/A N/A

In the above Table 9, HARQ-ACK(i) represents an ACK/NACK result for ani-th data unit. In the above Table 9, discontinuous transmission (DTX)means that there is no data unit to be transmitted for the correspondingHARQ-ACK(i) or that the UE does not detect the data unit correspondingto the HARQ-ACK(i). According to the above Table 9, a maximum of fourPUCCH resources (n_(PUCCH,0) ⁽¹⁾, n_(PUCCH,1) ⁽¹⁾, n_(PUCCH,2) ⁽¹⁾, andn_(PUCCH,3) ⁽¹⁾) are provided, and b(0) and b(1) are two bitstransmitted by using a selected PUCCH.

For example, if the UE successfully receives all of four data units, theUE transmits 2-bit (1,1) using n_(PUCCH,1) ⁽¹⁾.

If the UE fails in decoding in first and third data units and succeedsin decoding in second and fourth data units, the US transmits bits (1,0)using n_(PUCCH,3) ⁽¹⁾.

In ACK/NACK channel selection, if there is at least one ACK, the NACKand the DTX are coupled with each other. The reason for this is that acombination of the reserved PUCCH resource and the QPSK symbol may notall ACK/NACK states. However, if there is no ACK, the DTX is decoupledfrom the NACK.

In this case, the PUCCH resource linked to the data unit correspondingto one definite NACK may also be reserved to transmit signals ofmultiple ACKs/NACKs.

General ACK/NACK Transmission

In the LTE-A system, it considers transmitting, via a specific ULcomponent carrier (CC), a plurality of ACK/NACK information/signals fora plurality of PDSCHs transmitted via a plurality of DL CCs. To thisend, unlike ACK/NACK transmission using PUCCH format 1a/1b in theexisting Rel-8 LTE, it may consider to transmit a plurality of ACK/NACKinformation/signals by channel-coding (e.g., Reed-Muller code,Tail-biting convolutional code) a plurality of ACK/NACK information andthen using PUCCH format 2 or a new PUCCH format (i.e., E-PUCCH format)of the following block spreading based modified type.

A block spreading scheme is a scheme for modulating control signaltransmission using an SC-FDMA method, unlike the existing PUCCH format 1series or 2 series. As illustrated in FIG. 8, a symbol sequence may bespread on a time domain using an orthogonal cover code (OCC) and may betransmitted. Control signals of a plurality of UEs may be multiplexed onthe same RB using the OCC. In case of the PUCCH format 2 describedabove, one symbol sequence is transmitted over the time domain, and thecontrol signals of the plurality of UEs are multiplexed using a cyclicshift (CS) of a CAZAC sequence. On the other hand, in the case of theblock spreading based PUCCH format (e.g., PUCCH format 3), one symbolsequence is transmitted over a frequency domain, and the control signalsof the plurality of UEs are multiplexed using a time domain spreadingusing the OCC.

FIG. 16 illustrates an example of generating and transmitting 5 SC-FDMAsymbols during one slot in a wireless communication system to which thedisclosure may be applied.

FIG. 16 illustrates an example of generating and transmitting fiveSC-FDMA symbols (i.e., data part) using an OCC of the length 5 (or SF=5)in one symbol sequence during one slot. In this case, two RS symbols maybe used during one slot.

In the example of FIG. 16, the RS symbol may be generated from a CAZACsequence, to which a specific cyclic shift value is applied, and may betransmitted in the form in which a predetermined OCC is applied (ormultiplied) over a plurality of RS symbols. Further, in the example ofFIG. 8, if it is assumed that 12 modulation symbols are used for eachOFDM symbol (or SC-FDMA symbol) and each modulation symbol is generatedby QPSK, the maximum number of bits which can be transmitted on one slotis 24 bits (=12×2). Thus, the number of bits which can be transmitted ontwo slots is a total of 48 bits. If a PUCCH channel structure of theblock spreading scheme is used as described above, control informationof an extended size can be transmitted as compared to the existing PUCCHformat 1 series and 2 series.

For convenience of description, such a channel coding based method fortransmitting a plurality of ACKs/NACKs using the PUCCH format 2 or theE-PUCCH format is referred to as a multi-bit ACK/NACK codingtransmission method. The method refers to a method for transmitting anACK/NACK coded block generated by channel-coding ACK/NACK information ordiscontinuous transmission (DTX) information (representing that a PDCCHhas not been received/detected) for PDSCHs of a plurality of DL CCs. Forexample, if the UE operates in a SU-MIMO mode on any DL CC and receivestwo codewords (CWs), the UE may transmit a total of 4 feedback states ofACK/ACK, ACK/NACK, NACK/ACK, and NACK/NACK per CW on the DL CC, or mayhave up to 5 feedback states including until DTX. If the UE receives asingle CW, the UE may have up to 3 states of ACK, NACK, and DTX (if NACKand DTX are identically processed, the UE may have a total of two statesof ACK and NACK/DTX). Thus, if the UE aggregates up to 5 DL CCs andoperates in an SU-MIMO mode on all the CCs, the UE may have up to 55transmittable feedback states, and the size of an ACK/NACK payload forrepresenting these states is a total of 12 bits (if DTX and NACK areidentically processed, the number of feedback states is 45, and the sizeof the ACK/NACK payload for representing these states is a total of 10bits).

In the above ACK/NACK multiplexing (i.e., ACK/NACK selection) methodapplied to the existing Rel-8 TDD system, the method may basicallyconsider an implicit ACK/NACK selection method that uses implicit PUCCHresources (i.e., linked to a lowest CCE index) corresponding to PDCCHscheduling each PDSCH of the corresponding UE, in order to secure PUCCHresources of each UE. The LTE-A FDD system basically considers aplurality of ACK/NACK transmissions for a plurality of PDSCHs, which istransmitted via a plurality of DL CCs, via one specific UL CC that isUE-specifically configured. To this end, the LTE-A FDD system considersan ACK/NACK selection method using an implicit PUCCH resource linked toPDCCH (i.e., linked to a lowest CCE index n_CCE, or linked to n_CCE andn_CCE+1) that schedules a specific DL CC, or some of DL CCs, or all DLCCs, or a combination of the corresponding implicit PUCCH resource andan explicit PUCCH resource that is previously reserved to each UE viaRRC signaling.

The LTE-A TDD system may also consider a situation in which a pluralityof CCs is aggregated (i.e., CA). Hence, it may consider transmitting aplurality of ACK/NACK information/signals for a plurality of PDSCHs,which is transmitted via a plurality of DL subframes and a plurality ofCCs, via a specific CC (i.e., AN/CC) in UL subframes corresponding tothe corresponding plurality of DL subframes. In this instance, unlikethe LTE-A FDD system mentioned above, the LTE-A TDD system may considera method (i.e., full ACK/NACK) for transmitting a plurality ofACKs/NACKs corresponding to the maximum number of CWs, that can betransmitted via all the CCs assigned to the UE, in all of a plurality ofDL subframes (i.e., SFs), or a method (i.e., bundles ACK/NACK) fortransmitting ACKs/NACKs by applying ACK/NACK bundling to CW and/or CCand/or SF domain to reduce the total number of ACKs/NACKs to betransmitted (here, the CW bundling means that ACK/NACK bundling for CWis applied to each DL SF per each CC, the CC bundling means thatACK/NACK bundling for all or some of CCs is applied to each DL SF, andthe SF bundling means that ACK/NACK bundling for all or some of DL SFsis applied to each CC. Characteristically, as a SF bundling method, itmay consider an ACK-counter method which informs the total number ofACKs (or the number of some of the ACKs) per CC with respect to allPDSCHs or DL grant PDCCHs received for each CC). In this instance, amulti-bit ACK/NACK coding or an ACK/NACK selection based ACK/NACKtransmission method may be configurably applied according to a size ofan ACK/NACK payload per UE, i.e., a size of an ACK/NACK payload for fullor bundled ACK/NACK transmission that is configured for each UE.

ACK/NACK Transmission for LTE-A

The LTE-A system supports transmitting, via a specific UL CC, aplurality of ACK/NACK information/signals for a plurality of PDSCHswhich are transmitted via a plurality of DL CCs. To this end, unlikeACK/NACK transmission using PUCCH format 1a/1b in the existing Rel-8LTE, a plurality of ACK/NACK information may be transmitted through aPUCCH format 3.

FIG. 17 illustrates an ACK/NACK channel structure for PUCCH format 3with a normal CP.

As illustrated in FIG. 17, a symbol sequence is transmitted bytime-domain spreading by an orthogonal cover code (OCC) and maymultiplex control signals of multiple UEs on the same RB using the OCC.In the PUCCH format 2 mentioned above, one symbol sequence istransmitted over a time domain and performs the UE multiplexing using acyclic shift of a CAZAC sequence. On the other hand, in the case of thePUCCH format 3, one symbol sequence is transmitted over a frequencydomain and performs the UE multiplexing using the time-domain spreadingbased on the OCC. FIG. 17 illustrates a method for generating andtransmitting five SC-FDMA symbols from one symbol sequence using OCC oflength-5 (spreading factor=5). In an example of FIG. 17, a total of twoRS symbols have been used during one slot, but various applicationsincluding a method of using three RS symbols and using the OCC ofspreading factor=4, etc. may be considered. In this case, the RS symbolmay be generated from a CAZAC sequence with a specific cyclic shift andmay be transmitted in the form in which a specific OCC is applied (ormultiplied) to a plurality of RS symbols of the time domain. In theexample of FIG. 17, if it is assumed that 12 modulation symbols are usedfor each SC-FDMA symbol and each modulation symbol uses QPSK, themaximum number of bits which can be transmitted on each slot is 24 bits(=12×2). Thus, the number of bits which can be transmitted on two slotsis a total of 48 bits.

For convenience of description, such a channel coding based method fortransmitting a plurality of ACKs/NACKs using the PUCCH format 2 or theE-PUCCH format is referred to as a “multi-bit ACK/NACK coding”transmission method. The method refers to a method for transmitting anACK/NACK coded block generated by channel-coding ACK/NACK information orDTX information (representing that a PDCCH has not beenreceived/detected) for PDSCHs of a plurality of DL CCs. For example, ifthe UE operates in a SU-MIMO mode on any DL CC and receives twocodewords (CWs), the UE may transmit a total of 4 feedback states ofACK/ACK, ACK/NACK, NACK/ACK, and NACK/NACK per CW on the DL CC, or mayhave up to 5 feedback states including until DTX. If the UE receives asingle CW, the UE may have up to 3 states of ACK, NACK, and DTX (if NACKand DTX are identically processed, the UE may have a total of two statesof ACK and NACK/DTX). Thus, if the UE aggregates up to 5 DL CCs andoperates in an SU-MIMO mode on all the CCs, the UE may have up to 55transmittable feedback states, and the size of an ACK/NACK payload forrepresenting these states is a total of 12 bits (if DTX and NACK areidentically processed, the number of feedback states is 45, and the sizeof the ACK/NACK payload for representing these states is a total of 10bits).

In the above ACK/NACK multiplexing (i.e., ACK/NACK selection) methodapplied to the existing Rel-8 TDD system, the method may basicallyconsider an implicit ACK/NACK selection method that uses implicit PUCCHresources (i.e., linked to a lowest CCE index) corresponding to PDCCHscheduling each PDSCH of the corresponding UE, in order to secure PUCCHresources of each UE. The LTE-A FDD system basically considers aplurality of ACK/NACK transmissions for a plurality of PDSCHs, which istransmitted via a plurality of DL CCs, via one specific UL CC that isUE-specifically configured. To this end, the LTE-A FDD system considersan “ACK/NACK selection” method using an implicit PUCCH resource linkedto PDCCH (i.e., linked to a lowest CCE index n_CCE, or linked to n_CCEand n_CCE+1) that schedules a specific DL CC, or some of DL CCs, or allDL CCs, or a combination of the corresponding implicit PUCCH resourceand an explicit PUCCH resource that is previously reserved to each UEvia RRC signaling.

The LTE-A TDD system may also consider a situation in which a pluralityof CCs is aggregated (i.e., CA). Hence, it may consider transmitting aplurality of ACK/NACK information/signals for a plurality of PDSCHs,which is transmitted via a plurality of DL subframes and a plurality ofCCs, via a specific CC (i.e., AN/CC) in UL subframes corresponding tothe corresponding plurality of DL subframes. In this instance, unlikethe LTE-A FDD system mentioned above, the LTE-A TDD system may considera method (i.e., full ACK/NACK) for transmitting a plurality ofACKs/NACKs corresponding to the maximum number of CWs, that can betransmitted via all the CCs assigned to the UE, in all of a plurality ofDL subframes (i.e., SFs), or a method (i.e., bundles ACK/NACK) fortransmitting ACKs/NACKs by applying ACK/NACK bundling to CW and/or CCand/or SF domain to reduce the total number of ACKs/NACKs to betransmitted (here, the CW bundling means that ACK/NACK bundling for CWis applied to each DL SF per each CC, the CC bundling means thatACK/NACK bundling for all or some of CCs is applied to each DL SF, andthe SF bundling means that ACK/NACK bundling for all or some of DL SFsis applied to each CC. Characteristically, as a SF bundling method, itmay consider an “ACK-counter” method which informs of the total numberof ACKs (or the number of some ACKs) per CC for all PDSCHs or DL grantPDCCHs received for each CC). In this instance, a “multi-bit ACK/NACKcoding” or an “ACK/NACK selection” based ACK/NACK transmission methodmay be configurably applied according to a size of an ACK/NACK payloadper UE, i.e., a size of an ACK/NACK payload for the full or bundledACK/NACK transmission that is configured for each UE.

In a next-generation system, in order to satisfy requirements in variousapplication fields, a situation(s) in which a transmission time interval(TTI) can be variously set for all of or a specific physical channeland/or physical signal may be considered.

For example, when communication is performed between a base station(e.g., eNB or gNB) and a user equipment (UE) according to a scenario,for the purpose of reducing latency, a TTI used for the transmission ofa physical channel, such as a PDCCH/PDSCH/PUSCH/PUCCH, may be setsmaller than 1 subframe (i.e., 1 msec). Hereinafter, in the disclosure,a physical channel to which a short transmission time unit is appliedcompared to the existing transmission time unit (e.g., 1 subframe) maybe represented in a form in which (s) has been added to the existingchannel (e.g., sPDCCH/sPDSCH/sPUSCH/sPUCCH). Furthermore, a plurality ofphysical channels may be present within a single subframe (e.g., 1 msec)with respect to a single user equipment or a plurality of UEs. A TTI maybe differently set for each of the physical channels.

Hereinafter, in the embodiments proposed in the disclosure, forconvenience of description, proposed methods and examples are describedbased on the existing LTE system. In this case, a TTI is a commonsubframe size in an LTE system and may be 1 msec (hereinafter a normalTTI). Furthermore, a short TTI (sTTI) denotes a value smaller than the 1msec, and may be a single orthogonal frequency-division multiplexing(OFDM) symbol or a-plurality-of-OFDM symbol unit or a singlecarrier-frequency division multiple access (SC-FDMA) symbol unit.

For example, if a subcarrier spacing is subframes of 15 kHz, thesubframe may be split into 6 subslots based on Table 10. In this case, asubslot unit may correspond to the above sTTI unit.

Table 10 shows an example of the number of (OFDM) symbols in othersubslots of an i-th subframe (subframe i).

TABLE 10 Subslot number 0 1 2 3 4 5 Slot number 2i 2i + 1 Uplink subslot0, 1, 2 3, 4 5, 6 0, 1 2, 3 4, 5, 6 pattern Downlink subslot 0, 1, 2 3,4 5, 6 0, 1 2, 3 4, 5, 6 pattern 1 Downlink subslot 0, 1 2, 3, 4 5, 6 0,1 2, 3 4, 5, 6 pattern 2

Specifically, in the case of FDD in an LTE system, 10 subframes, 20slots or 60 subslots may be used for downlink transmission and 10subframes, 20 slots or 60 subslots may be used for UL transmissionwithin each 10 msec interval. In this case, the UL transmission and thedownlink transmission may be separated on a frequency domain. A userequipment cannot perform transmission and reception at the same time inthe case of a half-duplex FDD operation, but has not such restriction inthe case of a full-duplex FDD operation.

Hereinafter, in the embodiments proposed in the disclosure, forconvenience of description, in describing the proposed methods, a casewhere a short TTI (i.e., if a TTI length is smaller than a subframe) hasbeen assumed, but the methods proposed in the disclosure may be extendedand applied to a case where a TTI is longer than a subframe or is 1 msecor more. Furthermore, particularly, in a next-generation system (e.g.,the NR system), a short TTI may be introduced in a form in which thenumerology (e.g., subcarrier spacing) is increased. Even in this case,the methods proposed in the disclosure may be extended and applied.

That is, hereinafter, for convenience of description, the disclosure isdescribed based on an LTE system, but corresponding contents may also beapplied to a technology in which other waveforms and/or frame structuresare used, such as a new radio access technology (new RAT or NR). Ingeneral, in the disclosure, the case of an sTTI (<1 msec), a long TTI(=1 msec) or a longer TTI (>1 msec) is assumed.

Furthermore, a symbol, subslot slot, subframe and frame described in thefollowing embodiments described in the disclosure may correspond todetailed examples of a given time unit (e.g., transmission time unit)used in a wireless communication system. That is, in applying themethods proposed in the disclosure, a time unit described in thedisclosure may be substituted with other time units applied in otherwireless communication systems and applied.

Furthermore, the embodiments described in the disclosure have beenmerely divided for convenience of description, and some methods and/orsome configurations of an embodiment may be substituted with a methodand/or configuration of another embodiment or they may be combined andapplied.

First Embodiment

First, if the transmission of a subslot unit is scheduled, a method oftransmitting and receiving a PDSCH by considering DMRS sharing(hereinafter DMRS sharing) is described. In the disclosure, DMRS sharingmay mean a method of sharing a DMRS between (contiguously scheduled,disposed or assigned) PDSCHs.

Specifically, in the case of a subslot-PDSCH (i.e., PDSCH scheduled in asubslot unit), DMRS sharing may be permitted in order to reduce overheadattributable to a DMRS. In this case, in order to prevent performancedegradation of channel estimation, DMRS sharing may be permitted betweentwo subslots only. If DMRS sharing is applied, a rule has been definedso that a corresponding DMRS is always mapped to the former subslot oftwo subslots by considering the processing time of a user equipment.

According to the current standard (e.g., 3GPP standard), if it isindicated that a user equipment has not detected sDCI in an (n−1)-thsubslot (hereinafter subslot #n−1) and a DMRS is not present in an n-thsubslot (hereinafter subslot #n) through sDCI detected in the subslot#n, the user equipment does not expect the decoding of a subslot-PDSCHin the subslot #n.

In the disclosure, sDCI transmitted (or forwarded) and detected in asubslot #n and/or a subslot #n−1 may mean sDCI for a DL allocationusage, that is, DL assignment sDCI. Furthermore, the corresponding sDCImay correspond to a control channel (e.g., PDCCH or subslot-PDCCH)transmitted (or forwarded) and detected in a subslot #n and/or a subslot#n−1.

However, as described above, assuming that a rule has been defined, ifsDCI detected by a user equipment in a subslot #n−1 indicates that aDMRS is not present in the subslot #n−1 and sDCI detected by a userequipment in a subslot #n indicates that a DMRS is not present in thesubslot #n, ambiguity for the behavior of the user equipment may occur.Such a case may occur when the user equipment has mis-detected sDCI inthe subslot #n and/or the subslot #n−1 or may occur due to the erroneousscheduling of a base station.

Accordingly, a rule may be defined so that a user equipment does notexpect scheduling, such as the above case. In other words, a rule may bedefined so that a user equipment does not expect that a DMRS is notpresent in sDCI detected in contiguous subslots. That is, a userequipment may be configured to not expect that sDCIs detected in asubslot #n and subslot #n−1 indicate a DMRS absence in the subslot #nand a DMRS absence in the subslot #n−1, respectively. This may mean thata base station does not schedule that the sDCIs detected in the subslot#n and the subslot #n−1 indicate a DMRS absence in the subslot #n and aDMRS absence in the subslot #n−1.

And/or if it has been indicated or configured to a user equipment that aDMRS is not present in each subslot based on sDCI detected in contiguoussubslots (i.e., subslot #n and subslot #n−1), the user equipment may beconfigured to not expect (or to require) the decoding of a PDSCH in acorresponding subslot (i.e., subslot #n). Alternatively, in the abovecase, the user equipment may be configured to skip PDSCH decoding in thecorresponding subslot #n. In this case, a rule may be defined so thatthe user equipment reports (to the base station) HARQ-ACK informationfor the corresponding PDSCH (i.e., PDSCH in the subslot #n). Forexample, the HARQ-ACK information may be NACK information for thecorresponding PDSCH.

Furthermore, as in the above description, a case where it is indicatedto a user equipment that a DMRS is not present in a subslot #n throughsDCI detected in the subslot #n is assumed. In this case, if resourceallocation (e.g., physical resource block group (PRG) or physicalresource block (PRB)) by sDCI detected in a subslot #n−1 does notinclude resource allocation by the sDCI detected in the subslot #n, aproblem may occur due to the DMRS absence in relation to the PDSCHprocessing of the user equipment in the subslot #n. That is, if a PDSCHresource(s) in the subslot #n−1 does not include the PDSCH resource inthe subslot #n, PDSCH processing in a corresponding subslot may beproblematic because a DMRS is not present in the subslot #n.

By considering such a point, in the situation in which it has beenindicated to a user equipment that a DMRS is not present in a subslot #nthrough sDCI detected in the subslot #n, a rule may be defined so thatresource allocation in the subslot #n corresponds to a subset relationwith resource allocation in a subslot #n−1. For example, the subsetrelation may mean that the resource allocation in the subslot #n is thesame as the resource allocation in the subslot #n−1 or is included inthe resource allocation in the subslot #n−1.

And/or in the situation in which it has been indicated to a userequipment that a DMRS is not present in a subslot #n through sDCIdetected in the subslot #n, if resource allocation by sDCI detected in asubslot #n−1 is not the same as resource allocation by sDCI detected inthe subslot #n or does not include the resource allocation by the sDCIdetected in the subslot #n, the user equipment may be configured to notexpect (or require) that it should decode a PDSCH in a correspondingsubslot (i.e., subslot #n). Alternatively, in the above case, the userequipment may be configured to skip PDSCH decoding in the correspondingsubslot #n. In this case, a rule may be defined so that the userequipment reports (to a base station) HARQ-ACK information for acorresponding PDSCH (i.e., PDSCH in the subslot #n). For example, theHARQ-ACK information may be NACK information for the correspondingPDSCH.

Furthermore, in the situation in which it has been indicated to a userequipment that a DMRS is not present in a subslot #n through sDCIdetected in the subslot #n, a method of determining whether to decode aPDSCH by considering the number of resources (e.g., the number ofresource blocks (RBs)) non-overlapped between resource allocation in asubslot #n−1 and resource allocation in the subslot #n may also beconsidered.

For example, if the number of resources overlapped between resourceallocation in a subslot #n−1 and resource allocation in a subslot #n isless than a given value, a user equipment may be configured to decode aPDSCH in the subslot #n.

In contrast, if the number of resources overlapped between resourceallocation in the subslot #n−1 and resource allocation in the subslot #nis the given value or more, the user equipment may be configured to notexpect (or require) the decoding of a PDSCH in a corresponding subslot(i.e., the subslot #n). Alternatively, in the above case, the userequipment may be configured to skip PDSCH decoding in the correspondingsubslot #n. In this case, a rule may be defined so that the userequipment reports (to a base station) HARQ-ACK information (e.g., NACKinformation) for the corresponding PDSCH (i.e., a PDSCH in the subslot#n).

Furthermore, according to an LTE system (particularly, according to thestandard of a current LTE system), (DL) DMRS sharing between subslotsbelonging to different subframes may not be permitted. Accordingly, ifit has been indicated to a user equipment that a DMRS is not present ina subslot #0 through sDCI detected in the subslot #0, the correspondinguser equipment cannot obtain a DMRS for demodulating a PDSCH received inthe subslot #0.

By considering such a point, a rule may be defined so that a userequipment does not expect that it will be indicated that a DMRS is notpresent through sDCI detected in a subslot #0. In other words, a rulemay be defined so that the user equipment assumes that a DMRS is presentin sDCI detected in the subslot #0. That is, the corresponding userequipment may be configured to assume that it will be indicated that aDMRS is present in the subslot #0 through sDCI detected in the subslot#0.

And/or in the situation in which it has been indicated to a userequipment that a DMRS is not present in a subslot #0 through sDCIdetected in the subslot #0, the corresponding user equipment may beconfigured to not expect (or require) that it should decode a PDSCH inthe subslot #0. Alternatively, in the above case, the user equipment maybe configured to skip PDSCH decoding in the corresponding subslot #0. Inthis case, a rule may be defined so that the user equipment reports (toa base station) HARQ-ACK information for the corresponding PDSCH (i.e.,a PDSCH in the subslot #0). For example, the HARQ-ACK information may beNACK information for the corresponding PDSCH.

Furthermore, according to an LTE system (particularly, according to thestandard of a current LTE system), a DL subslot pattern may bedifferently configured (or constructed) depending on the number ofsymbols in a PDCCH control region. In this case, the subslot pattern maybe represented like Table 10. As a detailed example, if the number ofsymbols in a PDCCH control region is 1 or 3, a DL subslot pattern mayfollow the DL subslot pattern 1 of Table 10. If the number of symbols ina PDCCH control region is 2, a DL subslot pattern may follow the DLsubslot pattern 2 of Table 10. Furthermore, only if the number ofsymbols in a PDCCH control region is 1, a DMRS-based PDSCH may bescheduled in a subslot #0. Accordingly, in order for a DMRS for thePDSCH of a subslot #1 to be shared from the subslot #0, it is possibleonly when the condition is established. If not, the user equipmentcannot obtain a DMRS for the demodulation of the PDSCH of the subslot#1.

By considering such a point, if the number of symbols in a PDCCH controlregion is 2 or 3, a rule may be defined so that a user equipment doesnot expect that the absence of a DMRS in a corresponding subslot isindicated through sDCI detected in a subslot #1. In other words, a rulemay be defined so that the user equipment assumes that a DMRS is presentin the sDCI detected in the subslot #1. That is, the user equipment maybe configured to assume that the presence of a DMRS in a correspondingsubslot is indicated through the sDCI detected in the subslot #1.

And/or in the situation in which the number of symbols in a PDCCHcontrol region is 2 or 3, if it has been indicated to a user equipmentthat a DMRS is not present in a subslot #1 through sDCI detected in thesubslot #1, the corresponding user equipment may be configured to notexpect (or require) that it should decode a PDSCH in the subslot #1.Alternatively, in the above case, the user equipment may be configuredto skip PDSCH decoding in the corresponding subslot #1. In this case, arule may be defined so that the user equipment reports (to a basestation) HARQ-ACK information for the corresponding PDSCH (i.e., PDSCHin the subslot #1). For example, the HARQ-ACK information may be NACKinformation for the corresponding PDSCH.

FIGS. 18 and 19 and the following description in connection therewithregard methods and apparatuses for operating a UE and a base stationwhich perform transmission and reception of a data channel (e.g., aPDSCH or PUSCH) as proposed herein. Although the methods of FIGS. 18 and19 are described in connection with the PDSCH for ease of description,the methods may also be applicable to various data channel and/ordemodulation reference signals used in wireless communication systems.

Referring to FIG. 18, a case where a user equipment is configured toreceive or not receive a PDSCH in a specific subslot (i.e., specificTTI) based on the method(s) described in the present embodiment isassumed. Furthermore, in the method described in FIG. 18, a case whereDCI (in this case, DCI may correspond to a PDCCH) and/or a PDSCH isscheduled in a subslot unit is assumed.

First, the user equipment may receive first DCI (e.g., theaforementioned sDCI) for the scheduling of a first PDSCH in a first TTI(e.g., subslot #n−1) (S1805). For example, the first DCI may includeinformation indicating whether a DMRS for the first PDSCH is present inthe first TTI, information on resource allocation (e.g., PRB or PRG) forthe first PDSCH, etc.

Thereafter, the user equipment may receive second DCI (e.g., theaforementioned sDCI) for the scheduling of a second PDSCH in a secondTTI (e.g., the subslot #n) (S1810). For example, the second DCI mayinclude information indicating whether a DMRS for the second PDSCH ispresent in the second TTI, information on resource allocation (e.g., PRBor PRG) for the second PDSCH, etc. In this case, the second TTI may meana time unit consecutively disposed on a time domain with respect to thefirst TTI.

In this case, the user equipment may determine whether to receive (i.e.,decode) the second PDSCH based on the first DCI and the second DCI(S1815). Specifically, if the PDSCH absence of the second DMRS isindicated or configured in the second TTI by the second DCI, the userequipment may be configured to determine whether to receive the secondPDSCH by considering (all of) information included in the first DCI andinformation included in the second DCI.

For example, as described above in the present embodiment, if it hasbeen indicated or configured to a user equipment that a DMRS is notpresent in each TTI through (s)DCIs detected in a contiguous first TTI(e.g., subslot #n−1) and second TTI (e.g., subslot #n), thecorresponding user equipment may be configured to not expect that itshould decode a PDSCH (i.e., second PDSCH) in the second TTI (e.g.,subslot #n). Alternatively, in the above case, the corresponding userequipment may be configured to skip the decoding of the second PDSCH. Inthis case, a rule may be defined so that the corresponding userequipment reports, to a base station, HARQ-ACK information (e.g., NACKinformation) for the second PDSCH.

For another example, as described above in the present embodiment, inthe situation in which it has been indicated to a user equipment that aDMRS is not present in a second TTI through (s)DCI detected in thesecond TTI (e.g., subslot #n), if resource allocation by (s)DCI detectedin a first TTI (e.g., subslot #n−1) is not the same as or does notinclude resource allocation by the (s)DCI detected in the second TTI,the user equipment may be configured to not expect (or require) that itshould decode a PDSCH (i.e., the second PDSCH) in the second TTI.Alternatively, in the above case, the user equipment may be configuredto skip the decoding of the second PDSCH. In this case, a rule may bedefined so that the user equipment reports HARQ-ACK information (e.g.,NACK information) for the second PDSCH to a base station.

In connection with this, in an implementational aspect, theabove-described UE operations may be specifically implemented by the UEs2220 and 2320 shown in FIGS. 22 and 23. For example, the above-describedUE operations may be performed by the processors 2221 and 2321 and/orthe radio frequency (RF) units (or modules) 2223 and 2325.

In a wireless communication system, a UE receiving a data channel (e.g.,a PDSCH) may include a transmitter for transmitting wireless signals, areceiver for receiving wireless signals, and a processor functionallyconnected with the transmitter and the receiver. Here, the transmitterand the receiver (or transceiver) may be referred to as RF units (ormodules) for transmitting and receiving wireless signals.

For example, the processor may control the RF unit to receive a firstDCI (e.g., the above-described sDCI) for scheduling a first PDSCH in afirst TTI (e.g., the above-described subslot #n−1). As an example, thefirst DCI may include, e.g., information indicating whether a DMRS forthe first PDSCH is present in the first TTI and information for resourceallocation (e.g., PRB or PRG) for the first PDSCH.

Thereafter, the processor may control the RF unit to receive a secondDCI (e.g., the above-described sDCI) for scheduling a second PDSCH in asecond TTI (e.g., the above-described subslot #n). As an example, thesecond DCI may include, e.g., information indicating whether a DMRS forthe second PDSCH is present in the second TTI and information forresource allocation (e.g., PRB or PRG) for the second PDSCH. At thistime, the second TTI may mean a time unit which is placed continuouslywith the first TTI in the time domain.

At this time, the processor may perform control to determine whether toreceive (i.e., decode) the second PDSCH based on the first DCI and thesecond DCI. Specifically, where the absence of the DMRS of the secondPDSCH is indicated or set in the second TTI by the second DCI, theprocessor may be configured to determine whether to receive the secondPDSCH considering (both) information contained in the first DCI andinformation contained in the second DCI.

For example, as described above in the instant embodiment, where the UEreceives an indication or setting of the absence of a DMRS in each TTIby the (s) DCIs detected in the continuous first TTI (e.g., subslot#n−1) and second TTI (e.g., subslot #n), the processor may be configurednot to expect decoding of the PDSCH (i.e., the second PDSCH) in thesecond TTI (e.g., subslot #n). Or, in the above-described case, theprocessor may be configured to skip decoding of the second PDSCH. Atthis time, there may be defined a rule to allow the UE to reportHARQ-ACK information (e.g., NACK information) for the second PDSCH tothe base station.

As another example, as described above in the instant embodiment, if theresource allocation by the (s)DCI detected in the first TTI (e.g.,subslot #n−1) is not identical to the resource allocation by the (s)DCIdetected in the second TTI or this is not included in the context wherethe UE has received an indication of the absence of the DMRS in thesecond TTI via the (s)DCI detected in the second TTI (e.g., subslot #n),the processor may be configured not to expect (or be required for)decoding of the PDSCH (i.e., the second PDSCH) in the second TTI. Or, inthe above-described case, the processor may be configured to skipdecoding of the second PDSCH. At this time, there may be defined a ruleto allow the UE to report HARQ-ACK information (e.g., NACK information)for the second PDSCH to the base station.

FIG. 19 is a flowchart illustrating example operations of a base stationto transmit a downlink data channel to which a method proposed accordingto an embodiment is applicable. FIG. 19 is intended merely forillustration purposes but not for limiting the scope of the disclosure.

Referring to FIG. 19, it is assumed that the UE does not, or isconfigured not to, receive a PDSCH in a specific subslot (i.e., aspecific TTI) based on the method(s) described in the instantembodiment. It is also assumed in the method described in connectionwith FIG. 19 that DCIs (which may correspond to PDCCHs) and/or PDSCHsare scheduled in subslot units.

The base station may transmit a first DCI (e.g., the above-describedsDCI) for scheduling a first PDSCH to the UE in a first TTI (e.g., theabove-described subslot #n−1) (S1905). As an example, the first DCI mayinclude, e.g., information indicating whether a DMRS for the first PDSCHis present in the first TTI and information for resource allocation(e.g., PRB or PRG) for the first PDSCH.

The base station may transmit a second DCI (e.g., the above-describedsDCI) for scheduling a second PDSCH to the UE in a second TTI (e.g., theabove-described subslot #n) (S1910). As an example, the second DCI mayinclude, e.g., information indicating whether a DMRS for the secondPDSCH is present in the second TTI and information for resourceallocation (e.g., PRB or PRG) for the second PDSCH. At this time, thesecond TTI may mean a time unit which is placed continuously with thefirst TTI in the time domain.

The base station may transmit the PDSCHs (i.e., the first PDSCH and thesecond PDSCH) to the UE based on the first DCI and the second DCI(S1915).

At this time, the UE may determine whether to receive (i.e., decode) thesecond PDSCH based on the first DCI and the second DCI. Specifically,where the absence of the DMRS of the second PDSCH is indicated or set inthe second TTI by the second DCI, the UE may be configured to determinewhether to receive the second PDSCH considering (both) informationcontained in the first DCI and information contained in the second DCI.

For example, as described above in the instant embodiment, where the UEreceives an indication or setting of the absence of a DMRS in each TTIby the (s) DCIs detected in the continuous first TTI (e.g., subslot#n−1) and second TTI (e.g., subslot #n), the UE may be configured not toexpect decoding of the PDSCH (i.e., the second PDSCH) in the second TTI(e.g., subslot #n). Or, in the above-described case, the UE may beconfigured to skip decoding of the second PDSCH. At this time, there maybe defined a rule to allow the UE to report HARQ-ACK information (e.g.,NACK information) for the second PDSCH to the base station.

As another example, as described above in the instant embodiment, if theresource allocation by the (s)DCI detected in the first TTI (e.g.,subslot #n−1) is not identical to the resource allocation by the (s)DCIdetected in the second TTI or this is not included in the context wherethe UE has received an indication of the absence of the DMRS in thesecond TTI via the (s)DCI detected in the second TTI (e.g., subslot #n),the UE may be configured not to expect (or be required for) decoding ofthe PDSCH (i.e., the second PDSCH) in the second TTI. Or, in theabove-described case, the UE may be configured to skip decoding of thesecond PDSCH. At this time, there may be defined a rule to allow the UEto report HARQ-ACK information (e.g., NACK information) for the secondPDSCH to the base station.

In connection with this, in an implementational aspect, theabove-described base station operations may be specifically implementedby the base stations 2210 and 2310 shown in FIGS. 22 and 23. Forexample, the above-described base station operations may be performed bythe processors 2211 and 2311 and/or the radio frequency (RF) units (ormodules) 2213 and 2315.

In a wireless communication system, a base station transmitting a datachannel (e.g., a PDSCH) may include a transmitter for transmittingwireless signals, a receiver for receiving wireless signals, and aprocessor functionally connected with the transmitter and the receiver.Here, the transmitter and the receiver (or transceiver) may be referredto as RF units (or modules) for transmitting and receiving wirelesssignals.

For example, the processor may control the RF unit to transmit a firstDCI (e.g., the above-described sDCI) for scheduling a first PDSCH to theUE in a first TTI (e.g., the above-described subslot #n−1) (S1905). Asan example, the first DCI may include, e.g., information indicatingwhether a DMRS for the first PDSCH is present in the first TTI andinformation for resource allocation (e.g., PRB or PRG) for the firstPDSCH.

The processor may control the RF unit to transmit a second DCI (e.g.,the above-described sDCI) for scheduling a second PDSCH to the UE in asecond TTI (e.g., the above-described subslot #n) (S1910). As anexample, the second DCI may include, e.g., information indicatingwhether a DMRS for the second PDSCH is present in the second TTI andinformation for resource allocation (e.g., PRB or PRG) for the secondPDSCH. At this time, the second TTI may mean a time unit which is placedcontinuously with the first TTI in the time domain.

The processor may control the RF unit to transmit the PDSCHs (i.e., thefirst PDSCH and the second PDSCH) to the UE based on the first DCI andthe second DCI (S1915).

At this time, the UE may determine whether to receive (i.e., decode) thesecond PDSCH based on the first DCI and the second DCI. Specifically,where the absence of the DMRS of the second PDSCH is indicated or set inthe second TTI by the second DCI, the UE may be configured to determinewhether to receive the second PDSCH considering (both) informationcontained in the first DCI and information contained in the second DCI.

For example, as described above in the instant embodiment, where the UEreceives an indication or setting of the absence of a DMRS in each TTIby the (s) DCIs detected in the continuous first TTI (e.g., subslot#n−1) and second TTI (e.g., subslot #n), the UE may be configured not toexpect decoding of the PDSCH (i.e., the second PDSCH) in the second TTI(e.g., subslot #n). Or, in the above-described case, the UE may beconfigured to skip decoding of the second PDSCH. At this time, there maybe defined a rule to allow the UE to report HARQ-ACK information (e.g.,NACK information) for the second PDSCH to the base station.

As another example, as described above in the instant embodiment, if theresource allocation by the (s)DCI detected in the first TTI (e.g.,subslot #n−1) is not identical to the resource allocation by the (s)DCIdetected in the second TTI or this is not included in the context wherethe UE has received an indication of the absence of the DMRS in thesecond TTI via the (s)DCI detected in the second TTI (e.g., subslot #n),the UE may be configured not to expect (or be required for) decoding ofthe PDSCH (i.e., the second PDSCH) in the second TTI. Or, in theabove-described case, the UE may be configured to skip decoding of thesecond PDSCH. At this time, there may be defined a rule to allow the UEto report HARQ-ACK information (e.g., NACK information) for the secondPDSCH to the base station.

Second Embodiment

Described next is a method of transmitting/receiving a PUSCH consideringDMRS sharing when transmission in subslot units is scheduled. In thedisclosure, DMRS sharing may mean a scheme of sharing a DMRS betweenPUSCHs (continuously scheduled, arranged, or allocated).

Also in this embodiment, the subslot configuration as shown in Table 10described above in connection with the first embodiment may apply. Forexample, one subframe (or frame) may include two slots, and each slotmay include three subslots.

Specifically, for the three subslots included in the first slot (e.g.,slot #2i) of the two slots, the first subslot (e.g., subslot #0) mayinclude three symbols (e.g., symbols #0, #1, and #2), the second subslot(e.g., subslot #1) may include two symbols (e.g., symbols #3 and #4),and the third subslot (e.g., subslot #2) may include two symbols (e.g.,symbols #5 and #6). For the three subslots included in the second slot(e.g., slot #2i+1) of the two slots, the first subslot (e.g., subslot#3) may include three symbols (e.g., symbols #0, #1, and #2), the secondsubslot (e.g., subslot #4) may include two symbols (e.g., symbols #3 and#4), and the third subslot (e.g., subslot #5) may include two symbols(e.g., symbols #5 and #6).

At this time, the start position (e.g., the start symbol) of the PUSCHtransmission and/or the mapping position (e.g., mapping symbol) relatedto the PUSCH transmission may be set and/or indicated dynamically via aDCI. Hereinafter, the DCIs mentioned below may be UL DCIs (i.e.,UL-related DCIs) (e.g., DCI formats 7-0A/7-0B) related to uplinkscheduling.

Typically, mapping of subslot-considered PUSCH and PUSCH-related DMRS toa physical resource may be performed as follows.

First, a method of mapping a subslot-unit PUSCH to a physical resourceis described.

In the case of the subslot-unit PUSCH, the start of mapping of thephysical resource may be determined based on a specific field (e.g.,DMRS-pattern field) in the relevant UL DCI format (i.e., the UL grant)and the UL subslot number in the subframe allocated for PUSCHtransmission. As an example, the start symbol index I for subslot-unitPUSCH transmission may be determined as shown in Table 11. Table 11represents an example of configuring a start symbol index forsubslot-unit PUSCH transmission.

TABLE 11 DMRS-pattern field in uplink- related DCI Uplink subslot numberformat [3] #0 #1 #2 #3 #4 #5 00 1 4 6 1 3 5 01 0 3 5 0 2 — 10 — 3 — 0 2— 11 — 3 — — 2 —

For example, where the value of the information (e.g., DMRS-patternfield) for the DMRS pattern of the UL DCI scheduling subslot #2indicates ‘01,’ the start symbol of the subslot-unit PUSCH transmissionmay be the sixth symbol (i.e., symbol #5) of the slot (i.e., the firstslot). As another example, where the value of the information for theDMRS pattern of the UL DCI scheduling subslot #4 indicates ‘11,’ thestart symbol of the subslot-unit PUSCH transmission may be the thirdsymbol (i.e., symbol #2) of the slot (i.e., the second slot).

Further, in the case of semi-persistent scheduling (SPS) (e.g., higherlayer parameter sps-ConfigUL-sTTI-r15 is set) set in the periodicity ofone subslot (e.g., semiPersistSchedIntervalUL-STTI-r15 is set as sTTI1)and the subslot-unit PUSCH transmission, the mapping may be started atthe symbol I which is based on the specific field (e.g., DMRS-patternfield) in the relevant UL DCI format (i.e., the UL grant). As anexample, the start symbol index for subslot-unit PUSCH transmission setas the SPS with a periodicity of one subslot may be determined as shownin Table 12. Table 12 represents another example of configuring a startsymbol index for subslot-unit PUSCH transmission.

TABLE 12 DMRS-pattern field in uplink- related DCI Uplink subslot numberformat [3] #0 #1 #2 #3 #4 #5 00 1 4 6 1 3 5 10 1 3 6 0 3 5

For example, where the value of the information for the DMRS pattern ofthe UL DCI scheduling subslot #2 indicates ‘00,’ the start symbol of thesubslot-unit PUSCH transmission may be the seventh symbol (i.e., symbol#6) of the slot (i.e., the first slot). As another example, where thevalue of the information for the DMRS pattern of the UL DCI schedulingsubslot #4 indicates ‘10,’ the start symbol of the subslot-unit PUSCHtransmission may be the fourth symbol (i.e., symbol #3) of the slot(i.e., the second slot).

Further, in the case of the subslot-unit PUSCH set as the SPS with aperiodicity larger than one subslot, the above-described PUSCH mappingmay be started at the symbol I according to the case where the‘DMRS-pattern field in uplink related DCI format’ in Table 12 is set to‘00.’

Described next is a method of mapping the DMRS related to thesubslot-unit PUSCH to the physical resource.

For each antenna port used for transmission of PUSCH, the PUSCH sequence({tilde over (r)}_(PUSCH) ^(({tilde over (p)}))(⋅)) may be multiplied bythe amplitude scaling factor (√{square root over (1+δ)}β_(PUSCH)) andmay sequentially be mapped to the resource block(s) (RB(s)), startingwith {tilde over (r)}_(PUSCH) ^(({tilde over (p)}))(0). Here, for anyone case of: i) a higher layer parameter ul-DMRS-IFDMA is configured,and the latest UL DCI includes a cyclic shift mapping-related field(e.g., Cyclic Shift Field mapping table for DMRS bit field) indicatingthe use of Table 13; or ii) the cyclic shift mapping-related field isconfigured in the latest UL DCI format 7 indicating the use of Table 14below, δ=1. Otherwise, δ=0.

Table 13 represents an example mapping relationship for the cyclicshift-related field.

TABLE 13 Cyclic Shift Field in uplink- related DCI n_(DMRS, λ) ⁽²⁾[w^((λ))(0) w^((λ))(1)] format [3] ω λ = 0 λ = 1 λ = 2 λ = 3 λ = 0 λ = 1λ = 2 λ = 3 000 1 0 6 3 9 [1 1]  [1 1]  [1 −1] [1 −1] 001 1 6 0 9 3 [1−1] [1 −1] [1 1]  [1 1]  010 1 3 9 6 0 [1 −1] [1 −1] [1 1]  [1 1]  011 04 10 7 1 [1 1]  [1 1]  [1 1]  [1 1]  100 0 2 8 5 11 [1 1]  [1 1]  [1 1] [1 1]  101 0 8 2 11 5 [1 −1] [1 −1] [1 −1] [1 −1] 110 0 10 4 1 7 [1 −1][1 −1] [1 −1] [1 −1] 111 1 9 3 0 6 [1 1]  [1 1]  [1 −1] [1 −1]

Table 14 represents an example of subslot-unit PUSCH and/or an exampleof slot-unit PUSCH.

TABLE 14 Cyclic Shift Field in uplink- related DCI n_(DMRS, λ) ⁽²⁾ ωformat [3] λ = 0 λ = 1 λ = 2 λ = 3 λ = 0 λ = 1 λ = 2 λ = 3 0 0 6 3 9 0 01 1 1 6 0 9 3 1 1 0 0

At this time, where the higher layer parameter ul-DMRS-IFDMA isconfigured, and the latest UL DCI includes a cyclic shiftmapping-related field (e.g., Cyclic Shift Field mapping table for DMRSbit field) indicating the use of Table 13, PUSCH mapping to the resourceelement (RE) (e.g., (k, l)) may be performed in the order of firstincreasing k for all the k values (i.e., frequency resource index)meeting k mod 2={tilde over (ω)}. Here, for the normal cyclic prefix,l=3 and, for the extended cyclic prefix, l=2, and {tilde over (ω)} maybe given by Table 13 above.

For the subslot-unit PUSCH, PUSCH mapping to the resource element may beperformed in the order of first increasing k for all the k values exceptfor the case where the cyclic shift mapping-related field is configuredin the latest UL DCI format 7 which indicates the use of Table 14. Inthis case, the mapping needs to be performed in the order of firstincreasing k only for the k values meeting k mod 2={tilde over (ω)}.

At this time, I (i.e., the time resource index) may be set based on thelatest UL DCI DMRS pattern information (e.g., DMRS-pattern field) andthe UL subslot number according to Table 15 or 16 below.

Table 15 represents an example DMRS transmission (or mapping) symbolindex configuration for the subslot-unit PUSCH.

TABLE 15 DMRS-pattern field in uplink- related DCI Uplink subslot numberformat [3] #0 #1 #2 #3 #4 #5 00 0 3 5 0 2 4 01 2 4 — 1 3 — 10 — — — 2 —— 11 — 5 — — 4 —

For example, where the value of the information for the DMRS pattern ofthe UL DCI scheduling subslot #1 indicates ‘01,’ it may be set and/orindicated to the UE that the DMRS for the subslot-unit PUSCHtransmission is transmitted (or mapped) in the fifth symbol (i.e.,symbol #4) of the slot (i.e., the first slot) for the subslot-unit PUSCHtransmission. As another example, where the value of the information forthe DMRS pattern of the UL DCI scheduling subslot #4 indicates ‘11,’ itmay be set and/or indicated to the UE that the DMRS for the subslot-unitPUSCH transmission is transmitted (or mapped) in the fifth symbol (i.e.,symbol #4) of the slot (i.e., the second slot) for the subslot-unitPUSCH transmission.

Table 16 represents another example DMRS transmission (or mapping)symbol index configuration for the subslot-unit PUSCH. It is assumed inTable 16 that subslot-unit PUSCH transmission is set as semi-persistentscheduling (SPS) (e.g., higher layer parameter sps-ConfigUL-sTTI-r15 isset) set with a periodicity (e.g., semiPersistSchedIntervalUL-STTI-r15is set to sTTI1) of one subslot.

TABLE 16 DMRS-pattern field in uplink- related DCI Uplink subslot numberformat [3] #0 #1 #2 #3 #4 #5 00 0 3 5 0 2 4 10 0 5 5 2 2 4

For example, where the value of the information for the DMRS pattern ofthe UL DCI scheduling subslot #2 indicates ‘00,’ it may be set and/orindicated to the UE that the DMRS for the subslot-unit PUSCHtransmission is transmitted (or mapped) in the sixth symbol (i.e.,symbol #5) of the slot (i.e., the first slot) for the subslot-unit PUSCHtransmission. As another example, where the value of the information forthe DMRS pattern of the UL DCI scheduling subslot #2 indicates ‘10,’ itmay be set and/or indicated to the UE that the DMRS for the subslot-unitPUSCH transmission is transmitted (or mapped) in the third symbol (i.e.,symbol #4) of the slot (i.e., the second slot) for the subslot-unitPUSCH transmission.

Further, in the case of the subslot-unit DMRS set as the SPS with aperiodicity larger than one subslot, the above-described DMRS mappingmay be started at the symbol I according to the case where the DMRSpattern information in Table 16 is set to ‘00.’ Further, where no symbol(I) values are defined for the UL subslot number, and where there is novalid start symbol index, no reference signal (e.g., DMRS) may betransmitted in association with the UL-related DCI format.

As described above, for the PUSCH scheduled via the DCI (e.g., UL DCI),information for the symbol (i.e., the OFDM symbol) to which the DMRS forthe PUSCH is mapped may be dynamically set and/or indicated. In otherwords, the base station may dynamically set and/or indicate, to the UE,the DMRS mapping position of the PUSCH via, e.g., a UL grant.

In this case, however, the UE's operation may become unclear dependingon a specific setting and/or indication combination.

For example, referring to Table 15, if the DMRS pattern information(e.g., DMRS-pattern field) in the DCI (e.g., UL grant DCI) schedulingsubslot #1 is indicated as ‘11,’ the UE may recognize the indication asa {D D|R} pattern. Here, ‘D’,‘R,’ and ‘|’ may mean the data-mappedsymbol, the reference signal (e.g., DMRS)-mapped symbol, and theinter-subslot boundary, respectively. In other words, if the UE receivesthe indication, the UE may be configured to map PUSCH data to twosymbols of subslot #1, map the DMRS to the first symbol of subslot #2,and perform PUSCH transmission.

At this time, additionally, if the DMRS pattern information in the DCI(e.g., UL grant DCI) scheduling subslot #2 is indicated as ‘01,’ the UEmay recognize the indication as a {D D} pattern. In other words, if theUE additionally receives the indication, the UE may be configured to mapPUSCH data to two symbols of subslot #2 and perform PUSCH transmission.

In this case, since the first symbol (i.e., symbol #5) of subslot #2 hasbeen set for the purpose of DMRS transmission by the prior-received DCI,an ambiguity may occur as to whether to transmit a DMRS or PUSCH data inthe symbol in which the UE's settings and/or indications conflict.

As another example, if the DMRS pattern information in the DCIscheduling subslot #2 is indicated as ‘00’ in the above example, the UEmay recognize the indication as a {R D} pattern. In other words, if theUE receives the indication, the UE may be configured to map DMRS to thefirst symbol of subslot #2 and map PUSCH data to the second symbol, andperform PUSCH transmission. In this case, no ambiguity as in the aboveexample arises.

However, if information by the DCI scheduling subslot #1 differs frominformation by the DCI scheduling subslot #2, an ambiguity may occur interms of the UE's operations. Here, the information by the DCIscheduling subslot #1 and/or the information by the DCI schedulingsubslot #2 may include at least one of cyclic shift information,interleaved frequency division multiple access (IFDMA) comb information,resource allocation information for PUSCH, precoding information, and/ornumber of layers.

In other words, if the information by the DCI scheduling subslot #1differs from the information by the DCI scheduling subslot #2, there mayoccur ambiguity as to which one of the two DCIs is based on for the UEto transmit DMRS at the first symbol of subslot #2 based on the cyclicshift, IFDMA comb, resource allocation, precoding information, and/ornumber of layers.

Thus, a need exists for operations of the UE receiving inconsistentsettings and/or indications in a plurality of DCIs for specific DMRStransmission as described above. To address the above-describedambiguity, proposed below are methods of operation of the UE receivinginconsistent settings and/or indications in a plurality of DCIs forspecific DMRS transmission according to the instant embodiment.

Some configurations and/or operations of the methods described below maybe replaced, or merged, with configurations and/or operations of othermethod. Although the description focuses on subslot-unit PUSCHscheduling for ease of description, the methods may also be applicableto scheduling in other transmission time units (e.g., frames, slots, orsymbols) and/or other channels (e.g., PDSCH or PUCCH).

Method 1)

It is assumed that the UE receives inconsistent (i.e., non-identical)settings and/or indications in a plurality of DCIs scheduling the PUSCHto be transmitted in subslot #n and subslot #n+k for specific DMRStransmission as described above. Here, n means a positive integerincluding zero, and k is a positive integer larger than 0. That is,subslot #n+k may mean the kth subslot after subslot #n.

A method that may be considered in this case is to configure the UE totransmit the DMRS using information by the DCI scheduling the PUSCH tobe first transmitted (i.e., the PUSCH in subslot #n) among the pluralityof DCIs. In other words, the UE may be configured to discard theinformation by the DCI scheduling the PUSCH to be transmitted later(i.e., the PUSCH in subslot #n+k). At this time, the DMRS may be onetransmitted at a specific symbol of subslot #n+k.

For example, where the UE receives inconsistent settings and/orindications via a plurality of DCIs, the UE may transmit the PUSCH (inthis case, the DMRS for the PUSCH may also be included) using at leastone of the DMRS pattern information, cyclic shift information, IFDMAcomb information, resource allocation (e.g., PUSCH RB(s)) information,precoding information, number-of-layers information and/or transmitpower control (TPC) information (e.g., TPC field) indicated by the DCIscheduling the PUSCH to be first transmitted among the plurality ofDCIs.

Further, in the above case, a rule may be set and/or defined to allowdata (i.e., PUSCH data, UL-SCH) not to be transmitted in subslot #n+k.

Method 2)

It is assumed that the UE receives inconsistent (non-identical) settingsand/or indications in the plurality of DCIs (i.e., UL DCIs for PUSCHscheduling) received in subslot #n and subslot #n+k for specific DMRStransmission as described above. Here, n means a positive integerincluding zero, and k is a positive integer larger than 0. That is,subslot #n+k may mean the kth subslot after subslot #n.

A method that may be considered in this case is to configure the UE totransmit the DMRS using information by the DCI first transmitted (i.e.,the DCI received in subslot #n) among the plurality of DCIs. In otherwords, the UE may be configured to discard the information by the DCIlater received (i.e., the DCI received in subslot #n+k). At this time,the DMRS may be one transmitted in the transmission time unit(transmission time interval) (e.g., subslot #n+k+m, where m is apositive integer) scheduled by the DCI received in subslot #n+k.

For example, where the UE receives inconsistent settings and/orindications via a plurality of DCIs, the UE may transmit the PUSCH (inthis case, the DMRS for the PUSCH may also be included) using at leastone of the DMRS pattern information, cyclic shift information, IFDMAcomb information, resource allocation (e.g., PUSCH RB(s)) information,precoding information, number-of-layers information and/or TPCinformation (e.g., TPC field) indicated by the DCI first received amongthe plurality of DCIs.

Further, in the above case, a rule may be set and/or defined to allowdata (i.e., PUSCH data, UL-SCH) not to be transmitted in subslot #n+k.

FIGS. 20 and 21 and the following description in connection therewithregard methods and apparatuses for operating a UE and a base stationwhich perform transmission and reception of a data channel (e.g., aPDSCH or PUSCH) as proposed herein. Although the methods of FIGS. 20 and21 are described in connection with the PUSCH for ease of description,the methods may also be applicable to various data channel and/ordemodulation reference signals used in wireless communication systems.

FIG. 20 is a flowchart illustrating example operations of a UE totransmit an uplink data channel to which a method proposed according toan embodiment is applicable. FIG. 20 is intended merely for illustrationpurposes but not for limiting the scope of the disclosure.

Referring to FIG. 20, it is assumed that the UE and/or base stationperforms PUSCH transmission/reception in specific transmission timeunits (e.g., the above-described subslot units) and that PUSCH (i.e.,data and/or DMRS) transmission/reception is performed based on theabove-described method 1) and/or method 2).

The UE may receive, from the base station, first downlink controlinformation (DCI) for scheduling the uplink data channel in the nthtransmission time unit (S2005). For example, the first DCI maycorrespond to the DCI scheduling the PUSCH to be first transmitted inthe above-described method 1) and/or the DCI first received in theabove-described method 2).

The UE may receive, from the base station, second downlink controlinformation (DCI) for scheduling the uplink data channel in the n+kthtransmission time unit (S2010). For example, the second DCI maycorrespond to the DCI scheduling the PUSCH to be later transmitted inthe above-described method 1) and/or the DCI later received in theabove-described method 2).

For example, as in the above-described method 1) and/or method 2), thefirst DCI and the second DCI each may include at least one ofinformation (e.g., DMRS-pattern field) for the demodulation referencesignal (DMRS) pattern related to the uplink data channel, informationfor the cyclic shift, information for the interleaved frequency divisionmultiple access (IFDMA) comb, information (e.g., PUSCH RB(s)) forresource allocation, information for precoding, information for thenumber of layers, and/or information (e.g., TPC field) for the TPC.

At this time, there may be an occasion where the information by thefirst DCI is inconsistent with the information by the second DCI. Here,the information by the first DCI may man information set and/orindicated by the first DCI, and the information by the second DCI maymean information set and/or indicated by the second DCI.

For example, as in the above-described method 1) and/or method 2), thecase where the information by the first DCI is inconsistent with theinformation by the second DCI may be i) inconsistency in the DMRSpattern information and/or ii) inconsistency in at least one of thecyclic shift information, the IFDMA comb information, resourceallocation information, precoding information, number-of-layersinformation, and/or TPC information (e.g., TPC field).

As a specific example, in the case i) above, the DMRS pattern includedin the first DCI may indicate DMRS transmission for the uplink datachannel in the first symbol in the n+kth transmission time unit, and theDMRS pattern included in the second DCI may not indicate DMRStransmission for the uplink data channel in the first symbol of then+kth transmission time unit. Further, in the case ii), the DMRS patternincluded in the first DCI and the DMRS pattern included in the secondDCI (both) may be presumed to indicate DMRS transmission of the uplinkdata channel in the first symbol in the n+kth transmission time unit.

As described above, if the information by the first DCI is inconsistentwith the information by the second DCI, the UE may transmit the firstDCI-based uplink data channel to the base station (S2015). For example,as in the above-described method 1), the UE may transmit the PUSCH(i.e., PUSCH data and/or PUSCH DMRS) based on the DCI scheduling thePUSCH to be first transmitted. As another example, as in theabove-described method 2), the UE may transmit the PUSCH (i.e., PUSCHdata and/or PUSCH DMRS) based on the first-received DCI. In this case,the second DCI may be discarded (from the transmission of the uplinkdata channel) by the UE.

Further, as described above, in steps S2005 and S2010 described above, kmay be 1, and the nth transmission time unit may be placed continuouslywith the n+kth transmission time unit.

As described above, the nth transmission time unit and the n+kthtransmission time unit each may be a subslot including two or threeorthogonal frequency division multiplexing (OFDM) symbols.

In connection with this, in an implementational aspect, theabove-described UE operations may be specifically implemented by the UEs2220 and 2320 shown in FIGS. 22 and 23. For example, the above-describedUE operations may be performed by the processors 2221 and 2321 and/orthe radio frequency (RF) units (or modules) 2223 and 2325.

In a wireless communication system, a UE receiving a data channel (e.g.,a PDSCH) may include a transmitter for transmitting wireless signals, areceiver for receiving wireless signals, and a processor functionallyconnected with the transmitter and the receiver. Here, the transmitterand the receiver (or transceiver) may be referred to as RF units (ormodules) for transmitting and receiving wireless signals.

For example, the processor may control the RF unit to receive, from thebase station, the first downlink control information (DCI) forscheduling the uplink data channel in the nth transmission time unit.For example, the first DCI may correspond to the DCI scheduling thePUSCH to be first transmitted in the above-described method 1) and/orthe DCI first received in the above-described method 2).

For example, the processor may control the RF unit to receive, from thebase station, the second downlink control information (DCI) forscheduling the uplink data channel in the n+kth transmission time unit.For example, the second DCI may correspond to the DCI scheduling thePUSCH to be later transmitted in the above-described method 1) and/orthe DCI later received in the above-described method 2).

For example, as in the above-described method 1) and/or method 2), thefirst DCI and the second DCI each may include at least one ofinformation (e.g., DMRS-pattern field) for the demodulation referencesignal (DMRS) pattern related to the uplink data channel, informationfor the cyclic shift, information for the interleaved frequency divisionmultiple access (IFDMA) comb, information (e.g., PUSCH RB(s)) forresource allocation, information for precoding, information for thenumber of layers, and/or information (e.g., TPC field) for the TPC.

At this time, there may be an occasion where the information by thefirst DCI is inconsistent with the information by the second DCI. Here,the information by the first DCI may man information set and/orindicated by the first DCI, and the information by the second DCI maymean information set and/or indicated by the second DCI.

For example, as in the above-described method 1) and/or method 2), thecase where the information by the first DCI is inconsistent with theinformation by the second DCI may be i) inconsistency in the DMRSpattern information and/or ii) inconsistency in at least one of thecyclic shift information, the IFDMA comb information, resourceallocation information, precoding information, number-of-layersinformation, and/or TPC information (e.g., TPC field).

As a specific example, in the case i) above, the DMRS pattern includedin the first DCI may indicate DMRS transmission for the uplink datachannel in the first symbol in the n+kth transmission time unit, and theDMRS pattern included in the second DCI may not indicate DMRStransmission for the uplink data channel in the first symbol of then+kth transmission time unit. Further, in the case ii), the DMRS patternincluded in the first DCI and the DMRS pattern included in the secondDCI (both) may be presumed to indicate DMRS transmission of the uplinkdata channel in the first symbol in the n+kth transmission time unit.

As described above, if the information by the first DCI is inconsistentwith the information by the second DCI, the processor may control the RFunit to transmit the first DCI-based uplink data channel to the basestation. For example, as in the above-described method 1), the processormay control the RF unit to transmit the PUSCH (i.e., PUSCH data and/orPUSCH DMRS) based on the DCI scheduling the PUSCH to be firsttransmitted. As another example, as in the above-described method 2),the processor may control the RF unit to transmit the PUSCH (i.e., PUSCHdata and/or PUSCH DMRS) based on the first-received DCI. In this case,the second DCI may be discarded (from the transmission of the uplinkdata channel) by the UE.

Further, as described above, k may be 1, and the nth transmission timeunit may be placed continuously with the n+kth transmission time unit.

As described above, the nth transmission time unit and the n+kthtransmission time unit each may be a subslot including two or threeorthogonal frequency division multiplexing (OFDM) symbols.

FIG. 21 is a flowchart illustrating example operations of a base stationto receive an uplink data channel to which a method proposed accordingto an embodiment is applicable; FIG. 21 is intended merely forillustration purposes but not for limiting the scope of the disclosure.

Referring to FIG. 21, it is assumed that the UE and/or base stationperforms PUSCH transmission/reception in specific transmission timeunits (e.g., the above-described subslot units) and that PUSCH (i.e.,data and/or DMRS) transmission/reception is performed based on theabove-described method 1) and/or method 2).

The base station may transmit, to the UE, first downlink controlinformation (DCI) for scheduling the uplink data channel in the nthtransmission time unit (S2105). For example, the first DCI maycorrespond to the DCI scheduling the PUSCH to be first transmitted inthe above-described method 1) and/or the DCI first received in theabove-described method 2).

The base station may transmit, to the UE, second downlink controlinformation (DCI) for scheduling the uplink data channel in the nthtransmission time unit (S2110). For example, the second DCI maycorrespond to the DCI scheduling the PUSCH to be later transmitted inthe above-described method 1) and/or the DCI later received in theabove-described method 2).

For example, as in the above-described method 1) and/or method 2), thefirst DCI and the second DCI each may include at least one ofinformation (e.g., DMRS-pattern field) for the demodulation referencesignal (DMRS) pattern related to the uplink data channel, informationfor the cyclic shift, information for the interleaved frequency divisionmultiple access (IFDMA) comb, information (e.g., PUSCH RB(s)) forresource allocation, information for precoding, information for thenumber of layers, and/or information (e.g., TPC field) for the TPC.

At this time, there may be an occasion where the information by thefirst DCI is inconsistent with the information by the second DCI. Here,the information by the first DCI may man information set and/orindicated by the first DCI, and the information by the second DCI maymean information set and/or indicated by the second DCI.

For example, as in the above-described method 1) and/or method 2), thecase where the information by the first DCI is inconsistent with theinformation by the second DCI may be i) inconsistency in the DMRSpattern information and/or ii) inconsistency in at least one of thecyclic shift information, the IFDMA comb information, resourceallocation information, precoding information, number-of-layersinformation, and/or TPC information (e.g., TPC field).

As a specific example, in the case i) above, the DMRS pattern includedin the first DCI may indicate DMRS transmission for the uplink datachannel in the first symbol in the n+kth transmission time unit, and theDMRS pattern included in the second DCI may not indicate DMRStransmission for the uplink data channel in the first symbol of then+kth transmission time unit. Further, in the case ii), the DMRS patternincluded in the first DCI and the DMRS pattern included in the secondDCI (both) may be presumed to indicate DMRS transmission of the uplinkdata channel in the first symbol in the n+kth transmission time unit.

As described above, if the information by the first DCI is inconsistentwith the information by the second DCI, the base station may receive thefirst DCI-based uplink data channel from the base station (S2115). Forexample, as in the above-described method 1), the base station mayreceive, from the UE, the PUSCH (i.e., PUSCH data and/or PUSCH DMRS)based on the DCI scheduling the PUSCH to be first transmitted. Asanother example, as in the above-described method 2), the base stationmay receive, from the UE, the PUSCH (i.e., PUSCH data and/or PUSCH DMRS)based on the first-received DCI. In this case, the second DCI may bediscarded (from the transmission of the uplink data channel) by the UE.

Further, as described above, in steps S2105 and S2110 described above, kmay be 1, and the nth transmission time unit may be placed continuouslywith the n+kth transmission time unit.

As described above, the nth transmission time unit and the n+kthtransmission time unit each may be a subslot including two or threeorthogonal frequency division multiplexing (OFDM) symbols.

In connection with this, in an implementational aspect, theabove-described base station operations may be specifically implementedby the base stations 2210 and 2310 shown in FIGS. 22 and 23. Forexample, the above-described base station operations may be performed bythe processors 2211 and 2311 and/or the radio frequency (RF) units (ormodules) 2213 and 2315.

In a wireless communication system, a UE receiving a data channel (e.g.,a PDSCH) may include a transmitter for transmitting wireless signals, areceiver for receiving wireless signals, and a processor functionallyconnected with the transmitter and the receiver. Here, the transmitterand the receiver (or transceiver) may be referred to as RF units (ormodules) for transmitting and receiving wireless signals.

For example, the processor may control the RF unit to transmit, to theUE, the first downlink control information (DCI) for scheduling theuplink data channel in the nth transmission time unit. For example, thefirst DCI may correspond to the DCI scheduling the PUSCH to be firsttransmitted in the above-described method 1) and/or the DCI firstreceived in the above-described method 2).

For example, the processor may control the RF unit to transmit, to theUE, the second downlink control information (DCI) for scheduling theuplink data channel in the n+kth transmission time unit. For example,the second DCI may correspond to the DCI scheduling the PUSCH to belater transmitted in the above-described method 1) and/or the DCI laterreceived in the above-described method 2).

For example, as in the above-described method 1) and/or method 2), thefirst DCI and the second DCI each may include at least one ofinformation (e.g., DMRS-pattern field) for the demodulation referencesignal (DMRS) pattern related to the uplink data channel, informationfor the cyclic shift, information for the interleaved frequency divisionmultiple access (IFDMA) comb, information (e.g., PUSCH RB(s)) forresource allocation, information for precoding, information for thenumber of layers, and/or information (e.g., TPC field) for the TPC.

At this time, there may be an occasion where the information by thefirst DCI is inconsistent with the information by the second DCI. Here,the information by the first DCI may man information set and/orindicated by the first DCI, and the information by the second DCI maymean information set and/or indicated by the second DCI.

For example, as in the above-described method 1) and/or method 2), thecase where the information by the first DCI is inconsistent with theinformation by the second DCI may be i) inconsistency in the DMRSpattern information and/or ii) inconsistency in at least one of thecyclic shift information, the IFDMA comb information, resourceallocation information, precoding information, number-of-layersinformation, and/or TPC information (e.g., TPC field).

As a specific example, in the case i) above, the DMRS pattern includedin the first DCI may indicate DMRS transmission for the uplink datachannel in the first symbol in the n+kth transmission time unit, and theDMRS pattern included in the second DCI may not indicate DMRStransmission for the uplink data channel in the first symbol of then+kth transmission time unit. Further, in the case ii), the DMRS patternincluded in the first DCI and the DMRS pattern included in the secondDCI (both) may be presumed to indicate DMRS transmission of the uplinkdata channel in the first symbol in the n+kth transmission time unit.

As described above, if the information by the first DCI is inconsistentwith the information by the second DCI, the processor may control the RFunit to receive the first DCI-based uplink data channel from the UE. Forexample, as in the above-described method 1), the processor may controlthe RF unit to receive, from the UE, the PUSCH (i.e., PUSCH data and/orPUSCH DMRS) based on the DCI scheduling the PUSCH to be firsttransmitted. As another example, as in the above-described method 2),the processor may control the RF unit to receive, from the UE, the PUSCH(i.e., PUSCH data and/or PUSCH DMRS) based on the first-received DCI. Inthis case, the second DCI may be discarded (from the transmission of theuplink data channel) by the UE.

Further, as described above, k may be 1, and the nth transmission timeunit may be placed continuously with the n+kth transmission time unit.

As described above, the nth transmission time unit and the n+kthtransmission time unit each may be a subslot including two or threeorthogonal frequency division multiplexing (OFDM) symbols.

It is apparent that since example schemes proposed herein may beincluded in one of the implementing methods of the disclosure, they maybe regarded as sorts of proposed schemes. The schemes proposed hereinmay be implemented independently, or some proposed schemes may becombined (or merged) together. A rule may be defined to allow the basestation to provide information as to whether to apply the schemesproposed herein (and/or information for the rules of the proposedmethods) to the UE via pre-defined signaling (e.g., physical layersignaling and/or higher layer signaling).

Overview of Apparatus to which the Disclosure May be Applied

FIG. 22 illustrates a block diagram of a wireless communicationapparatus to which a method proposed in the disclosure may be applied.

Referring to FIG. 22, a wireless communication system includes a basestation 2210 and a plurality of user equipments 2220 disposed within thearea of the base station 2210.

The base station and the user equipment may be represented as wirelessdevices, respectively.

The base station 2210 includes a processor 2211, a memory 2212 and aradio frequency (RF) unit 2213. The processor 2211 implements thefunction, process and/or method proposed in FIGS. 1 to 21. The layers ofa radio interface protocol may be implemented by the processor. Thememory is connected to the processor, and stores various pieces ofinformation for driving the processor. The RF unit is connected to theprocessor, and transmits and/or receives a radio signal.

The user equipment 2220 includes a processor 2221, a memory 2222 and anRF unit 2223.

The processor 2221 implements the function, process and/or methodproposed in FIGS. 1 to 21. The layers of a radio interface protocol maybe implemented by the processor 2221. The memory 2222 is connected tothe processor 2221, and stores various pieces of information for drivingthe processor 2221. The RF unit 2223 is connected to the processor 2221,and transmits and/or receives a radio signal.

The memory 2212, 2222 may be positioned inside or outside the processor2211, 2221 and may be connected to the processor 2211, 2221 by variouswell-known means.

Furthermore, the base station and/or the user equipment may have asingle antenna or multiple antennas.

The antenna 2214, 2224 functions to transmit and receive radio signals.

FIG. 23 is another example of a block diagram of a wirelesscommunication apparatus to which a method proposed in the disclosure maybe applied.

Referring to FIG. 23, a wireless communication system includes a basestation 2310 and multiple user equipments 2320 disposed within the basestation region. The base station may be represented as a transmissiondevice, and the user equipment may be represented as a reception device,and vice versa. The base station and the user equipment includeprocessors 2311 and 2321, memories 2314 and 2324, one or more Tx/Rxradio frequency (RF) modules 2315 and 2325, Tx processors 2312 and 2322,Rx processors 2313 and 2323, and antennas 2316 and 2326, respectively.The processor implements the above-described functions, processes and/ormethods. More specifically, in DL (communication from the base stationto the user equipment), a higher layer packet from a core network isprovided to the processor 2311. The processor implements the function ofthe L2 layer. In DL, the processor provides the user equipment 2320 withmultiplexing between a logical channel and a transport channel and radioresource allocation, and is responsible for signaling toward the userequipment. The TX processor 2312 implements various signal processingfunctions for the L1 layer (i.e., physical layer). The signal processingfunction facilitates forward error correction (FEC) in the userequipment, and includes coding and interleaving. A coded and modulatedsymbol is split into parallel streams. Each stream is mapped to an OFDMsubcarrier and multiplexed with a reference signal (RS) in the timeand/or frequency domain. The streams are combined using inverse fastFourier transform (IFFT) to generate a physical channel that carries atime domain OFDMA symbol stream. The OFDM stream is spatially precodedin order to generate multiple space streams. Each space stream may beprovided to a different antenna 2316 through an individual Tx/Rx module(or transmitter and receiver 2315). Each Tx/Rx module may modulate an RFcarrier into each space stream for transmission. In the user equipment,each Tx/Rx module (or transmitter and receiver 2325) receives a signalthrough each antenna 2326 of each Tx/Rx module. Each Tx/Rx modulerestores information modulated in an RF carrier and provides it to theRX processor 2323. The RX processor implements various signal processingfunctions of the layer 1. The RX processor may perform space processingon information in order to restore a given space stream toward the userequipment. If multiple space streams are directed toward the userequipment, they may be combined into a single OFDMA symbol stream bymultiple RX processors. The RX processor converts the OFDMA symbolstream from the time domain to the frequency domain using fast Fouriertransform (FFT). The frequency domain signal includes an individualOFDMA symbol stream for each subcarrier of an OFDM signal. Symbols oneach subcarrier and a reference signal are restored and demodulated bydetermining signal deployment points having the best possibility, whichhave been transmitted by the base station. Such soft decisions may bebased on channel estimation values. The soft decisions are decoded anddeinterleaved in order to restore data and a control signal originallytransmitted by the base station on a physical channel. A correspondingdata and control signal are provided to the processor 2321.

UL (communication from the user equipment to the base station) isprocessed by the base station 2310 in a manner similar to that describedin relation to the receiver function in the user equipment 2320. EachTx/Rx module 2325 receives a signal through each antenna 2326. EachTx/Rx module provides an RF carrier and information to the RX processor2323. The processor 2321 may be related to the memory 2324 storing aprogram code and data. The memory may be referred to as acomputer-readable medium.

In the disclosure, the wireless device may be a base station, a networknode, a transmission terminal, a reception terminal, a radio device, awireless communication device, a vehicle, an autonomous vehicle, anunmanned aerial vehicle (UAV) or drone, an artificial intelligence (AI)module, a robot, an augmented reality (AR) device, a virtual reality(VR) device, an MTC device, an IoT device, a medical device, a fintechdevice (or financial device), a security device, a weather/environmentdevice, or a device related to fourth industrial revolution or 5Gservice. For example, the drone may be an unmanned aerial vehicle thatmay be flown by wireless control signals. For example, the MTC deviceand IoT device may be devices that need no human involvement or controland may be, e.g., smart meters, vending machines, thermostats, smartbulbs, door locks, or various sensors. For example, the medical devicemay be a device for diagnosing, treating, mitigating, or preventingdisease or a device used for testing, replacing, or transforming thestructure or function, and may be, e.g., a piece of equipment fortreatment, surgery, (extracorporeal) diagnosis device, hearing aid, orprocedure device. For example, the security device may be a device forpreventing possible risks and keeping safe, which may include, e.g., acamera, a CCTV, or a blackbox. For example, the fintech device may be adevice capable of providing mobile payment or other financial services,which may include, e.g., a payment device or point-of-sales (PoS)device. For example, the weather/environment device may mean a devicethat monitors and forecasts weather/environment.

In the disclosure, the term ‘terminal’ may encompass, e.g., mobilephones, smartphones, laptop computers, digital broadcast terminals,personal digital assistants (PDAs), portable multimedia players (PMPs),navigation, slate PCs, tablet PCs, ultrabooks, wearable devices (e.g.,smartwatches, smart glasses, or head-mounted displays (HMDs), orfoldable devices. For example, the HMD, as a display worn on the human'shead, may be used to implement virtual reality (VR) or augmented reality(AR).

The aforementioned embodiments are achieved by a combination ofstructural elements and features of the disclosure in a predeterminedmanner. Each of the structural elements or features should be consideredselectively unless specified separately. Each of the structural elementsor features may be carried out without being combined with otherstructural elements or features. In addition, some structural elementsand/or features may be combined with one another to constitute theembodiments of the disclosure. The order of operations described in theembodiments of the disclosure may be changed. Some structural elementsor features of one embodiment may be included in another embodiment, ormay be replaced with corresponding structural elements or features ofanother embodiment. Moreover, it is apparent that some claims referringto specific claims may be combined with another claims referring to theother claims other than the specific claims to constitute the embodimentor add new claims by means of amendment after the application is filed.

The embodiments of the disclosure may be achieved by various means, forexample, hardware, firmware, software, or a combination thereof. In ahardware configuration, the methods according to the embodiments of thedisclosure may be achieved by one or more application specificintegrated circuits (ASICs), digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), processors, controllers,microcontrollers, microprocessors, etc.

In a firmware or software configuration, the embodiments of thedisclosure may be implemented in the form of a module, a procedure, afunction, etc. Software code may be stored in the memory and executed bythe processor. The memory may be located at the interior or exterior ofthe processor and may transmit data to and receive data from theprocessor via various known means.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the disclosure withoutdeparting from the spirit or scope of the disclosures. Thus, it isintended that the disclosure covers the modifications and variations ofthis disclosure provided they come within the scope of the appendedclaims and their equivalents.

INDUSTRIAL AVAILABILITY

Although the data transmission/reception schemes in the wirelesscommunication system according to the disclosure have been shown anddescribed in connection with examples applied to 3GPP LTE/LTE-A systems,the disclosure may also be applicable to other various wirelesscommunication systems, e.g., 5G systems, than 3GPP LTE/LTE-A systems.

1. A method for transmitting an uplink data channel by a user equipmentin a wireless communication system, the method comprising: receiving,from a base station, first downlink control information (DCI) forscheduling the uplink data channel in n-th subslot, receiving, from thebase station, second DCI for scheduling the uplink data channel inn+k-th subslot, and wherein the first DCI and the second DCI comprise,respectively, at least one of information for a cyclic shift,information for a Interleaved Frequency Division Multiple Access (IFDMA)comb, information for resource allocation, information for a precoding,and/or a number of layers, regarding the uplink data channel, andwherein, when at least one of the information for the cyclic shift, theinformation for the IFDMA comb, the information for the resourceallocation, the information for the precoding, and/or the number oflayers is inconsistent between the first DCI and the second DCI,transmitting, to the base station, the uplink data channel based on thefirst DCI, and wherein the second DCI is discarded by the userequipment.
 2. The method of claim 1, wherein the first DCI and thesecond DCI further comprise, respectively, information for aDemodulation Reference Signal (DMRS) pattern, regarding the uplink datachannel.
 3. The method of claim 2, further comprising: when theinformation for the DMRS pattern is inconsistent between the first DCIand the second DCI, transmitting an uplink data channel based on thefirst DCI to the base station, and wherein the second DCI is discardedby the user equipment.
 4. The method of claim 3, wherein a DMRS patternincluded in the first DCI represents that DMRS transmission for theuplink data channel in a first symbol of the n+k-th subslot, and whereina DMRS pattern included in the second DCI does not represents that theDMRS transmission for the uplink data channel in a first symbol of then+k-th subslot.
 5. (canceled)
 6. The method of claim 2, wherein a DMRSpattern included in the first DCI and a DMRS pattern included in thesecond DCI represent that DMRS transmission for the uplink data channelin a first symbol of the n+k-th subslot.
 7. The method of claim 1,wherein the k is one (1), and wherein the n-th subslot is contiguouslyassigned with the n+k-th subslot.
 8. The method of claim 1, wherein then-th subslot and the n+k-th subslot comprise, respectively, two or threeOrthogonal Frequency Division Multiplexing (OFDM) symbols.
 9. A userequipment for transmitting an uplink data channel in a wirelesscommunication system, the user equipment comprising: a transceiver fortransmitting and receiving a radio signal; and a processor operativelycoupled to the transceiver, wherein the processor is configured tocontrol to: receive, from a base station, first downlink controlinformation (DCI) for scheduling the uplink data channel in n-thsubslot, receive, from the base station, second DCI for scheduling theuplink data channel in n+k-th subslot, and wherein the first DCI and thesecond DCI comprise, respectively, at least one of information for acyclic shift, information for a Interleaved Frequency Division MultipleAccess (IFDMA) comb, information for resource allocation, informationfor a precoding, and/or a number of layers, regarding the uplink datachannel, and wherein, when at least one of the information for thecyclic shift, the information for the IFDMA comb, the information forthe resource allocation, the information for the precoding, and/or thenumber of layers is inconsistent between the first DCI and the secondDCI, transmit, to the base station, the uplink data channel based on thefirst DCI, and wherein the second DCI is discarded by the userequipment.
 10. The user equipment of claim 9, wherein the first DCI andthe second DCI further comprise, respectively, information for aDemodulation Reference Signal (DMRS) pattern, regarding the uplink datachannel.
 11. The user equipment of claim 10, wherein, when theinformation for the DMRS pattern is inconsistent between the first DCIand the second DCI, the processor controls to transmit an uplink datachannel based on the first DCI to the base station, and wherein thesecond DCI is discarded by the user equipment.
 12. The user equipment ofclaim 11, wherein a DMRS pattern included in the first DCI representsthat DMRS transmission for the uplink data channel in a first symbol ofthe n+k-th subslot, and wherein a DMRS pattern included in the secondDCI does not represents that the DMRS transmission for the uplink datachannel in a first symbol of the n+k-th subslot.
 13. (canceled)
 14. Theuser equipment of claim 9, wherein a DMRS pattern included in the firstDCI and a DMRS pattern included in the second DCI represent that DMRStransmission for the uplink data channel in a first symbol of the n+k-thsubslot.
 15. A base station for receiving an uplink data channel in awireless communication system, the base station comprising: atransceiver for transmitting and receiving a radio signal; and aprocessor operatively coupled to the transceiver, wherein the processoris configured to control to: transmit, to a user equipment, firstdownlink control information (DCI) for scheduling the uplink datachannel in n-th subslot, transmit, to the user equipment, second DCI forscheduling the uplink data channel in n+k-th subslot, and wherein thefirst DCI and the second DCI comprise, respectively, at least one ofinformation for a cyclic shift, information for a Interleaved FrequencyDivision Multiple Access (IFDMA) comb, information for resourceallocation, information for a precoding, and/or a number of layers,regarding the uplink data channel, and wherein, when at least one of theinformation for the cyclic shift, the information for the IFDMA comb,the information for the resource allocation, the information for theprecoding, and/or the number of layers is inconsistent between the firstDCI and the second DCI, receive, from the user equipment, the uplinkdata channel based on the first DCI, and wherein the second DCI isdiscarded by the user equipment.